chantelle rebello masters by research - qut...chantelle a. rebello, sara j. couperthwaite, graeme j....

COAL SEAM GAS WATER QUALITY AND IMPACTS

ON DOWNSTREAM TREATMENT TECHNOLOGIES

Chantelle Rebello

Masters by Research

Dr. Sara Couperthwaite

Prof. Graeme Millar

Prof. Leslie Dawes

Submitted in fulfilment of the requirements for the degree of

Master of Science (Research)

Faculty of Science and Engineering

Queensland University of Technology

2017

Coal Seam Gas Water Quality and Impacts on Downstream Treatment Technologies

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Keywords

CS water, beneficial use, coal seam gas, environmental management, Environmental Protection

Act 1994, Queensland, regulations, Surat Basin, surrogate indicators, principal component

analysis, water quality, reverse osmosis.


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Abstract

The coal seam gas (CSG) industry in Australia is of significant importance economically,

especially in Queensland where a substantial increase in the amount of gas extracted over

the past six years has occurred. CSG formation, relation to local geological features,

extraction approach and the potential impact/benefits of coal seam (CS) water has been

considered by reviewing the location of CSG wells in relation to each other, the depth of the

well in relation to the coal seam with which the CSG is associated, and the quality of the CS

water compared with the requirements for each beneficial use application. An outline of the

limited current legislative requirements on physical and chemical properties of CS water as

regulated by the Queensland Government is provided, as well as the current treatment

technologies used by the major CSG companies to ensure compliance with these

requirements. Water quality from 150 CSG production wells from the Surat Basin,

Queensland has been analysed and compared within and between multiple gas fields in a

small geographic area prior to any storage, disposal and treatment. Chemical analysis

revealed the CS water to have high bicarbonate, high sodium, and low calcium, low

magnesium and very low sulfate concentrations. The chemical analysis also confirmed that

the pre-treatment concentration levels of specific parameters such as sodium, chloride, total

dissolved solids, and sodium adsorption ratio were above that required for use by agricultural

and industrial sectors, therefore requiring treatment prior to use. This study has shown that

the amount of each type of mineral that comprises coal, such as clay, sulfide ores, oxide ores,

quartz and phosphates, may explain the water quality patterns by assessing the mineral

content of the associated CS water in relation to the chemical composition of Surat Basin coal

seams. Through the use of multivariate analysis, it has been shown, in these particular CS

water samples, that the depth of the CSG production well and the location of the CSG

production well does not show correlations for the CS water quality. The physical and

chemical parameters that have been analysed in this study will aid in the efficient

management of CS water and provide information to legislators so as to better understand

environmental impacts of pre-treatment and post treatment beneficial use of CS water. A

linear regression model has been developed which predicts values for sodium adsorption

ratio and total dissolved solids, for a wide range of CS water samples. The use of surrogate

indicators at the water source will aid in a more efficient management of CS water by CSG

industries. It was also shown that the design of an appropriate reverse osmosis (RO) system

for CS water treatment could be enhanced by examination of the wide range of CS water

compositions collected in this study from 3 CSG fields in the Surat Basin, with commercial


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software packages such as ROSA and IMS Design. The predictions of ROSA and IMS Design,

were found not to be completely in agreement, albeit the general consensus was that the

scaling potential of barium sulphate and calcium fluoride species was the primary concern

for CS water. Consequently, the use of anti-scalants and/or ion exchange softening was

proposed as being necessary to maximise the operational parameters of the RO unit.

Calculation of the Langelier Saturation Index (LSI) revealed that it was positive and that

calcium carbonate scaling may also be an issue to address. As such, lowering of the CS water

pH by acid addition was also determined to be useful in protecting the membranes from

fouling. It was concluded that the CS water types evaluated were not amenable to drinking

water use as the total dissolved solids content in the permeate was not always in accord with

regulatory guidelines. However, it was recommended that irrigation or stock watering may

be the preferred beneficial reuse options.


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Table of Contents

Keywords .................................................................................................................................................. i

Abstract ................................................................................................................................................... ii

Table of Contents ................................................................................................................................... iv

List of Figures ......................................................................................................................................... vi

List of Tables .......................................................................................................................................... vii

List of Abbreviations ............................................................................................................................. viii

List of Publications ................................................................................................................................. ix

Statement of Original Authorship ........................................................................................................... x

Acknowledgments .................................................................................................................................. xi

CHAPTER 1: INTRODUCTION ............................................................................................................ 1

Background ............................................................................................................................................. 1

Context .................................................................................................................................................... 1

Purposes .................................................................................................................................................. 1

Significance ............................................................................................................................................. 2

Thesis Outline .......................................................................................................................................... 4

CHAPTER 2: LITERATURE REVIEW .................................................................................................... 7

Gas Industry ............................................................................................................................................ 7

CS Water .................................................................................................................................................. 9

Geology and Stratigraphy ...................................................................................................................... 10

Water Catchment and Aquifers ............................................................................................................ 12

Extraction and Production of Coal Seam Gas ........................................................................................ 14

Legislative and RE-Use Options of CS Water ......................................................................................... 16

Treatment Technologies ....................................................................................................................... 26

Desalination Technologies .................................................................................................................... 31

Conclusions ........................................................................................................................................... 33

Implications ........................................................................................................................................... 33

CHAPTER 3: RESEARCH DESIGN ..................................................................................................... 35

Site Selection ......................................................................................................................................... 35

Sampling Program ................................................................................................................................. 36

Characterisation Techniques ................................................................................................................. 37

Quality Control ...................................................................................................................................... 40

Modelling .............................................................................................................................................. 40

Limitations ............................................................................................................................................. 46

CHAPTER 4: RESULTS & ANALYSIS – WATER QUALITY ................................................................... 47

Chemical Compoition of CS Water ........................................................................................................ 48

Descriptive Statistics ............................................................................................................................. 48


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Solution pH ............................................................................................................................................ 51

Alakalinity .............................................................................................................................................. 51

Sodium Ions ........................................................................................................................................... 52

Chloride Ions ......................................................................................................................................... 53

Hardness................................................................................................................................................ 54

Barium and Strontium Ions ................................................................................................................... 55

Aluminium and Iron Ions ....................................................................................................................... 57

Total Dissolved Soilds and Electrical Conductivity ................................................................................ 58

Sodium Adsorption Ratio ...................................................................................................................... 59

Total Suspended Solids ......................................................................................................................... 60

Fluoride and Bromide Ions .................................................................................................................... 61

Boron ................................................................................................................................................... 62

Silica ................................................................................................................................................... 63

Parameters Excluded from Analysis of CS Water .................................................................................. 63

CHAPTER 5: RESULTS & ANALYSIS – PRINCIPAL COMPONENT ANALYSIS ....................................... 65

CHAPTER 6: RESULTS & ANALYSIS – SURROGATE INDICATORS ...................................................... 72

CHAPTER 7: RESULTS & ANALYSIS – SCALING POTENTIAL & REVERSE OSMOSIS DESIGN ............... 80

Scaling Potential .................................................................................................................................... 80

Pre-Treatment Selection ....................................................................................................................... 86

Comparison of Permeate to Drinking Water, Irrigation Water and Stock Water Trigger Values ......... 87

CHAPTER 8: CONCLUSIONS ............................................................................................................ 95

Practical Implications ............................................................................................................................ 96

Future Work .......................................................................................................................................... 96

REFERENCES ................................................................................................................................... 98

APPENDIX A ................................................................................................................................. 110


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List of Figures

Figure 1: Extent of the Surat Basin .......................................................................................................... 8

Figure 2: pH and Bicarbonate Alkalinity as CaCO3 of CS water for the A, B and C Field in the Surat Basin ............................................................................................................................................. 52

Figure 3: Na+ and Cl- Values of CS water for the A, B and C Field in the Surat Basin ............................ 54

Figure 4: Ca2+ and Mg2+ Values of CS water for the A, B and C Field in the Surat Basin ........................ 56

Figure 5: Ba and Sr Values of CS water for the A, B and C Field in the Surat Basin ............................... 57

Figure 6: Al and Fe Values of CS water for the A, B and C Field in the Surat Basin ............................... 58

Figure 7: TDS and EC Values of CS water for the A, B and C Field in the Surat Basin ............................ 59

Figure 8: SAR Values of CS water for the A, B and C Field in the Surat Basin ........................................ 60

Figure 9: TSS Values of CS water for the A, B and C Field in the Surat Basin ........................................ 61

Figure 10: Br- and F- Values of CS water for the A, B and C Field in the Surat Basin .............................. 62

Figure 11: B and Si Values of CS water for the A, B and C Field in the Surat Basin ............................... 64

Figure 12: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field in the Surat basin.......................................................................................... 66

Figure 13: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field for the Juandah Coal Seam in the Surat Basin .............................................. 67

Figure 14: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field for the Taroom Coal Seam in the Surat Basin .............................................. 69

Figure 15: Measured SAR vs. Calculated SAR ........................................................................................ 73

Figure 16: Relationship between EC and Measured TDS ...................................................................... 74

Figure 17: Measured TDS vs. Calculated TDS ........................................................................................ 74

Figure 18: Measured TDS vs. Calculated TDS Wyoming USA [41] ......................................................... 76

Figure 19: Measured SAR vs. Calculated SAR Wyoming USA [41] ......................................................... 77

Figure 20: Measured TDS vs. Calculated TDS Utah USA [13] ................................................................ 78

Figure 21: Measured TDS vs. Calculated TDS Bowen Basin Australia [3] .............................................. 78

Figure 22: Field A Scaling Potential ROSA Data ..................................................................................... 82

Figure 23: Field B Scaling Potential ROSA Data ..................................................................................... 82

Figure 24: Field C Scaling Potential ROSA data ..................................................................................... 82

Figure 25: Field A Scaling Potential IMS Design Data ............................................................................ 84

Figure 26: Field B Scaling Potential IMS Design Data ............................................................................ 84

Figure 27: Field C Scaling Potential IMS Design Data ............................................................................ 84

Figure 28: Boron Concentration A, B and C Field .................................................................................. 91

Figure 29: TDS Concentration A, B and C Field ...................................................................................... 92

Figure 30: Sodium Concentration A, B and C Field ................................................................................ 93

Figure 31: Irrigation Water Drinking Water and Stock Water Trigger Level Sodium, Nitrate, Chloride and TDS ......................................................................................................................................... 94

Figure 32: Irrigation Water Drinking Water and Stock Water Trigger Level Barium and Boron ........... 94


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List of Tables

Table 1: Beneficial Use Approval Water Quality Requirements for Reuse of CS water in the Surat Basin ............................................................................................................................................. 19

Table 2: QGC Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin ............................................................................................................................. 19

Table 3: Origin Energy Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin ............................................................................................................. 21

Table 4: Arrow Energy Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin ............................................................................................................. 22

Table 5: Santos Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin ............................................................................................................................. 22

Table 6: CS Water Treatment Infrastructure in the Surat Basin for Major CSG Operating Companies 30

Table 7: Parameters Tested for CS water in the Surat Basin ................................................................. 37

Table 8: Values for ROSA Model Field A ................................................................................................ 43

Table 9: Values for ROSA Model Field B ................................................................................................ 44

Table 10: Values for ROSA Field C ......................................................................................................... 45

Table 11: Minimum and Maximum Values of Parameters Tested from Surat Basin CS water ............. 49

Table 12: Mean for Parameters Tested from Surat Basin CS water ...................................................... 50

Table 13: Parameters Excluded from Analysis for CS water in the Surat Basin .................................... 64

Table 14: Drinking Water and Irrigation Water Compared with Field A Permeate .............................. 88

Table 15: Drinking Water and Irrigation Water Compared with Field B Permeate............................... 89

Table 16: Drinking Water and Irrigation Water Compared with Field C Permeate ............................... 90


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List of Abbreviations

Atomic Adsorption Spectrophotometry AAS

Australian and New Zealand Guidelines for Fresh and Marine Water

Quality

ANZECC & ARMCANZ

Australian Laboratory Services ALS

Coal Seam CS

Coal seam gas CSG

Department of Environment and Heritage Protection DEHP

Inductively Coupled Plasma Atomic Emission Spectroscopy ICP-AES

Gigalitres GL

Great Artesian Basin GAB

Liquefied natural gas LNG

Limit of Reading LOR

Megalitres ML

Million years ago Ma

National Association of Testing Authorities NATA

National Environment Protection (Assessment of Site

Contamination) Measure 1999 Guidelines

NEMP

Petajoules PJ

Principal component PC

Principal component analysis PCA

Reverse osmosis RO

Reverse Osmosis System Analysis ROSA

Relative Percent Deviation RPD

United States of America US

World Health Organization WHO


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List of Publications

Chantelle A. Rebello, Sara J. Couperthwaite, Graeme J. Millar, Les A. Dawes “Understanding

coal seam associated water, regulations and strategies for treatment”, Journal of

Unconventional Oil and Gas Resources 13 (2016) 32–43.

Chantelle A. Rebello, Sara J. Couperthwaite, Graeme J. Millar, Les A. Dawes “Coal seam

water quality and the impact upon management strategies”, Journal of Petroleum Science

and Engineering, 150 (2017) 323-333.

Chantelle A. Rebello, Mariam Darestani, Sara J. Couperthwaite, Graeme J. Millar, Les A.

Dawes “Scaling Potential Assessment and Implications for Use of Coal Seam Produced

Water”, manuscript in preparation.


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Statement of Original Authorship

The work contained in this thesis has not been previously submitted to meet requirements for

an award at this or any other higher education institution. To the best of my knowledge and

belief, the thesis contains no material previously published or written by another person except

where due reference is made.

Signature:

Date: 3 November 2017

QUT Verified Signature


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Acknowledgments

I would like to thank my principal supervisor Dr Sara Couperthwaite, and my associate

supervisors Professor Graeme Millar and Professor Leslie Dawes for their considerable

assistance, time and support and for the opportunity to undertake this research project.

I would like to thank laboratory staff at Queensland University of Technology particularly

Kenneth Nuttall and Mitchell De Bruyn for their time and assistance in the laboratory with

analytic instruments and experimental support.

I would like to thank staff and students in the School of Chemistry, Physics and Mechanical

Engineering and the School of Earth, Environment and Biological Sciences, for their time at

meetings and critic of my research project. I would also like to thank the HDR staff in the

Science and Engineering Faculty for their administrative support.

I would like to thank Arrow Energy for information contained within, permission to publish,

and support during the preparation of this research project. I would also like to thank staff at

Arrow Energy for their assistance in the collection of samples, development of instruments

to facilitate the monitoring program and logistical support.

Chapter 1: Introduction

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1Chapter 1: Introduction

This chapter outlines the background and context of the study, the overarching objectives of the

study, and the significance of this research. Finally, it includes an outline of the remaining

chapters of the thesis.

BACKGROUND

The coal seam gas (CSG) industry in Australia is relatively new, and as such few studies have been

published regarding environmental management techniques for coal seam (CS) water. CS water

is produced during the extraction process of CSG. This research project was developed in order

to understand the physical and chemical composition of CS water in the Surat Basin in

Queensland. This research project also targeted the development of methods to analyse CS

water. In addition, an overview of the current legislation was provided and strategies for water

treatment investigated. This approach assisted with water quality assessment and the

subsequent selection of treatment technologies for CS water relevant to the beneficial reuse

application.

CONTEXT

This investigation of 150 production wells from the Surat Basin included: characterisation of

chemical and physical properties of CS water; identification of the influences on the water quality

including analysis of the location of each well; and the geological chemistry surrounding each

individual well (stratigraphy). An assessment of the water quality on the basis of the intended

application of the water, and ability to predict water quality parameters using univariate and

multivariate analysis was also investigated. This assessment was based on information available

from the Queensland Government that regulates the CSG Industry, as well as information on

current treatment technologies and re-use.

PURPOSE

The aim of this study was to provide an analysis and comparison of the chemical composition

of CS water within and between multiple gas fields in a small geographic location of the Surat

Basin, prior to any storage, disposal and treatment. In addition, an objective was to identify

differences between water chemistry and to identify relationships with depth and location

of the CSG production well using multivariate analysis. From this information, beneficial re-


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use options were explored, including the most appropriate and economical means to store

and treat CS water based on location, depth and regional geology. Selection of pre-treatment

methods and RO methods and membranes for parameters of significance was developed

from the water quality data. CS water quality parameters that can only be tested in

laboratories which are often situated long distances from the CSG basins, were correlated in

order to develop surrogate indicators. Ultimately, this work provided a basis for

management and treatment of CS water. The specific objectives associated with this study

included:

1. To analysis of the physical and chemical composition of CS water.

2. To identify patterns in the data using univariate and multivariate analysis and the

implications of the legislation and current treatment technologies being used in the Surat

Basin.

3. To develop surrogate indicators to predict key water quality parameters that can only be

tested in the laboratory.

4. Evaluate: how variations in concentration and composition of CS water impact RO

performance; what are the scaling potentials which can be expected for CS water

compositions; and which pre-treatment methods are recommended to minimise fouling

and scaling of RO membranes.

SIGNIFICANCE

This research provided fundamental knowledge regarding the variability of CS water and

assessed its composition based on the location of the aquifer associated with the coal seam

and the geology that surrounds it. Water quality correlations enabled predictive models for

CS water to be developed.

A demonstration was made of the impact of specific water quality parameters on the

beneficial re-use options that are legislated by the Queensland Government. Included was

the analysis of the treatment technologies that are currently being used by CSG operating

companies in the Surat Basin.

The identification of surrogate indicators for parameters that are only able to be tested in a

laboratory could reduce the cost and time associated with water sampling, enabling better

decisions to be made on water management.


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Knowing the variability of CS water and how this variability impacts water treatment

technologies such as RO, improves processing conditions and decisions that enable beneficial

reuse water to be produced.

This research project considered CS water quality in relation to the current government

legislation, and its current uses as beneficial reuse and the treatment technology required to

achieve these regulatory values.


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THESIS OUTLINE

Figure 1 (a): Outline of MSc Thesis Topic

Following a literature review (Chapter 2) a comparison of the current legislative requirements

was required in order to identify what use CS water has in Queensland. Understanding the

legislative requirements can play a major role in determining the effectiveness of this study

for the CSG industry in Australia. There are 4 major operating companies in the Surat Basin

CSG industry; QGC, Arrow Energy, Santos and Origin in which this study has focused. The

legislative requirements differ between these 4 CSG companies with each company

operating under many approvals (Environmental Authorities). A comparison has been made

of the differences between and within the CSG companies regulated water quality trigger

values.

Literature Review

Water Sampling

Program

Comparison of Legislative Requirements

for CS water Re-Use

Overview of Treatment Technologies

Used by Each CSG Operating Company

Univariate Analysis

Multivariate Analysis

Surrogate

Indicator

Development

Application of software tools such as ROSA

and IMS Design to assist with management

of RO Treatment


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Following the comparison of the legislative requirements it has been determined that a

review should be undertaken of the current treatment technologies being utilised by each

company. The treatment technologies in the Australian CSG Industry are similar for the

primary treatment technologies however are varied for the pre-treatment technologies. This

stage of the study attempted to assess the reason for the differences with suggestions such

as the final use of the CS water, water quality of the feed water and the, amount of water

being treated per day.

A water sampling program (Chapter 4 and 5) has been undertaken of CSG production wells

in the Surat Basin, Queensland. The water sampling program was undertaken to try to

identify patterns within the data and whether correlations existed due to the depth of the

coal seam and for the geology associated with the coal seam. This related to the legislative

requirements discussed earlier, as understanding the water quality and having the ability to

predict the water quality prior to CSG extraction or development of exploration wells and

fields will help with the management of the CS water in relation to the storage of CS water,

treatment technologies required and reuse opportunities.

The water sampling program generated a large amount of water quality data as there were

150 CSG production wells sampled and 48 parameters analysed. The water quality data was

required to be analysed using univariate and multivariate analysis in order to identify any

patterns present. The first stage was to use univariate analysis on each individual parameter

with a comparison made between 3 current operating production fields in the Surat Basin.

Particular parameters were chosen to be analysed simultaneously and were graphed to

determine if patterns could be developed from geology and depth. Further to this was a

multivariate analysis of the water quality data. The technique used was a chemometric

method. Principal component analysis was used to identify patterns based on location of the

well and the depth of the well. Depth was an indication of the coal seam in which the gas

was being extracted from; with the CS water being extracted from one of two coal seams in

Surat Basin for this study, one at a depth of approximately 400m (Juahdah) and the other at

a depth of approximately 800m (Taroom).

This study (Chapter 6) was focused on the CSG industry in Australia and particularly

Queensland in order to develop management strategies to assist with CSG water quality

management. In order to assess water quality some parameters needed to be sampled and

then sent to a laboratory to be tested. De to the large area (400 km in length) and


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remoteness of the Surat Basin this situation can mean an extended time period between the

time of the water sample and the water quality results. The implications of this for CSG

operating companies can include time delays, financial costs, and mismanagement of CS

water. Surrogate indicators have been used to assist with water quality analysis in other

industries. Surrogate indicators were used in this study to develop a method for testing CSG

water quality at the water source and predict parameters required to be known in order to

determine final use of the CS water or downstream treatment requirements. .

The final stage of this study (Chapter 7) was to assess the effect variable CS water quality

data had on RO as a primary treatment technology using ROSA and IMS Design simulation

software. RO has been used in the CSG industry for the treatment of brackish water and is

currently being used by all CSG companies in the Surat Basin. This simulation assisted with

the prediction of the pre-treatment technologies, antiscalant requirements and membrane

and membrane maintenance based on the water quality of the feed water (water input into

the system).

Chapter 2: Literature Review

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This chapter reviewed literature on the following topics: the CSG industry and economic

significance; an understanding of CS water both in Australia and overseas; the geology and

stratigraphy of the Surat Basin; water catchment and aquifer reserves of the Surat Basin; the

extraction process and production of CSG to the domestic energy market and as an export

commodity; the legislative requirements and options for beneficial re-use of CS water; and

an overview of the current treatment technologies currently used in the Surat Basin by the

four major CSG operating companies. In order to effectively manage the environmental

impact of the CSG industry this study explained the nature of the gas deposits, methods for

gas collection, the physicochemical composition of the by-product CS water and the

technologies available for water remediation. This review was of significance in relation to

the formulation of the most appropriate and cost effective management of CS water, while

simultaneously preserving existing water resources and the environment.

GAS INDUSTRY

CSG is an emerging industry in Australia and in particular Queensland where it is an important

part of the economy in terms of a domestic energy resource and also as a significant export

commodity [1-3]. Mining of CSG in the Surat Basin involves drilling of vertical wells from the

surface to within the coal seam, wherein the trapped gas is released by dewatering [4]. The

deeper the coal seam the higher the pressures acting on the seam [5]. As a consequence, a

substantial volume of water (termed CS water) is collected in retention basins with the water

quality being typically saline in character [6, 7].

Conventional gas sources have been exploited in Australia for several years, and in 2013-14,

24 million tonnes of liquefied natural gas (LNG) was exported from Western Australia, the

Northern Territory and Queensland with a combined revenue of A$16.4 billion [8].

Unconventional resources such as coal seam gas (CSG) have emerged more recently, and

now represent an important part of the Queensland economy in terms of an energy resource

for domestic consumption and export [1-3]. The CSG industry has been operating in

Queensland since the early 1990’s, with commercial production commencing in 1996 [3].

There were approximately 600 production wells drilled in Queensland in 2010-11 and annual

gas production has evolved from 2 petajoules (PJ) in 1997-98 to 234 PJ in 2010-11 [9]. The


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potential for CSG extraction in Queensland is due not only to the relatively shallow depths at

which the gas is present, but also the large quantity available, with approximately 64 % of

the proven and probable reserves found in the Surat Basin [10]. The Surat Basin (Figure 1) is

located along Eastern Australia, within the southern section of Queensland, occupying an

area of approximately 300,000 km2 [11].

Figure 1 (b) : Extent of the Surat Basin

It is predicted that the Surat Basin alone contains an estimated 33,000 PJ in methane reserves

[9]. The key geological feature of the Surat Basin is the Walloon Subgroup, which is a series

of volcanolithic sandstones, coal, mudstones and siltstones with a maximum thickness of

about 250 m [2]. The Walloon Subgroup is found at depths of approximately 200 to greater

than 800 m, which is amenable for CSG to be extracted relatively easily [10, 12]. Coal seams

found in the Walloon Subgroup are geologically predictable and found in large quantities [10,

13]. Other gas resources in Queensland include the Bowen, Galilee, and Clarence-Moreton

basins [14].

Regional context of this study


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CS WATER

Australia is prone to drought, with 70 % of the Australian continent receiving less than 500

mm of rain annually and as such it is classed as arid or semi-arid [15]. Therefore, the

sustainability of water resources is of major concern. One of the greatest challenges faced

by the CSG industry is the substantial volume of water produced during the gas extraction

process known as CS water. CS water is typically brackish in character which does not allow

it to be used for most applications without being treated due to a high salinity and variable

pH [7, 16]. In addition, the CS water has a highly variable chemical composition, and as such

a universal treatment method is not available [6]. This variability is significantly enhanced

when comparing the northern and southern ends of the Surat Basin, due to the sheer size of

this aquifer system, spanning over numerous geological compositions [17]. Similar variation

in the composition of coal seam gas water has been found in samples from the United States

(US). For example, Dahm et al. described an extensive study of several thousand wells from

the Rocky Mountain area and found a substantial range of salinities varying from a few

hundred mg/L total dissolved solids concentration to in excess of 35,000 mg/L [18]. Rice

(2003) reported that the Ferron coal seam gas fields also exhibited major changes in water

quality between individual wells [19]. Reasons for the disparity and complexity of the CS

water were outlined by Pashin et al. and included geological and hydrodynamic factors [20].

To aid selection of treatment options for the range of coal seam gas water types produced,

Plumlee et al. developed a software program which took into account a large selection of

operational parameters and options for beneficial reuse [21]. Knowledge of the CS water

characteristics in Australia is not as comprehensive compared to the US. Kinnon et al.

reported analysis of coal seam water from the Bowen Basin in Queensland, and generally the

total dissolved solids content was less than 10,000 mg/L [3]. The dominant dissolved species

were sodium, chloride and bicarbonate with minor amounts of alkaline earth ions,

potassium, fluoride, aluminum and iron.

In theory, the availability of CS water should represent an opportunity for local communities

due to the potential for beneficial reuse. However, public perception has been shown to

view CSG mining as a threat to water supplies [22]. Tan et al. proposed that this latter

viewpoint was partially due to a lack of information regarding the relationship between CSG

mining operations and aquifers [23]. Vink has also emphasized the dangers of


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misinformation inhibiting the development of the CSG industry and the need to accumulate

data into one resource [24].

Consequently, it would be useful to gain a better understanding of the pertinent issues that

encompass the geological aspects, extraction, legislation, reuse and treatment of CS water.

There is a need to improve the management of CS water produced in the CSG industry, not

only in Australia but in other areas of the world such as the US [25]. This research focused in

particular upon the Surat Basin, as it is the major CSG region on the Eastern coast of Australia.

The aim of this paper was to facilitate water conservation in Australia and to guide

appropriate management practices for the anticipated quantities of CS water.

GEOLOGY AND STRATIGRAPHY

The Surat Basin is composed of sedimentary rocks from the Jurassic to Cretaceous periods

[26] and is part of the Great Artesian Basin (GAB), which encompasses approximately one-

fifth of Australia [27]. There are a number of groundwater systems located within the GAB

and these include the Condamine Alluvium (up to 150 m thick), the Kumbarilla Beds (100 to

200 m thick) and the Walloon Coal Measure (100 and 500 m thick). Underlying these systems

are the Hutton Sandstone/Marburg Subgroups (120 to 180 m thick) and the Precipice

Sandstone systems [17]. The Condamine Alluvium is situated west of the Surat Basin

connected by the Kumbarilla Ridge to the east of the Clarence-Moreton Basin [26]. The key

lithostratigraphic units of the Surat Basin include the Kumbarilla Beds (comprising of Mooga,

Gubberamunda and Springbok sandstones) overlying the Walloon Coal Measures, and the

Walloon Coal Measures overlying Hutton/Marburg Sandstone [26]. The groundwater

systems of these geological formations are complex and the aquifers potentially

interconnected. Younger Tertiary basalts cap the Walloon Coal Measures and

Hutton/Marburg Sandstone to the east of the Condamine Alluvium [26]. The Kumbarilla Beds

are described as restricted outcrop (visual exposure of bedrock) [26]. The Hutton/Marburg

Sandstone is made up of sandstone with interbedded siltstone, shale and mudstone [26].

The Walloon Coal Measures are comprised of fine to medium grained, labile, argillaceous

sandstone, siltstone, mudstone and coal, with minor calcareous sandstone, impure

limestone and ironstone, and coals (located within the upper 75% of the geological sequence)

[26]. The geological sequence of the Surat Basin was deposited over time from the late

Triassic, 206 – 227 million years ago (Ma) to the early Cretaceous, 99 – 144 Ma, while the

Walloon Coal Measures were predominately deposited from the Early Middle Jurassic to the

Late Jurassic (197 – 145 Ma) [12, 26].


© 2016 Page 11

The coal measures of the Walloon Subgroup are of Middle to Late Jurassic age [12] and make

up the north and east portion of the Surat Basin [10, 12]. The Walloon Subgroup was named

and then re-named, between 1907 and 1973, into three sub-units: the Taroom Coal

Measures, Tangalooma Sandstone, and Juandah Coal Measures [12]. Coals are located in the

lower Taroom Coal Measures and the upper Juandah Coal Measures [10]. The Juandah Coal

Measures and the Taroom Coal Measures contain a number of seams each individually

named. The Juandah Coal Measures includes the Juandah, Kogan, Macalister (upper and

lower), Nangram, Wambo, Iona and Argyle [12], while the Taroom Coal Measures include

Auburn, Bulwer and Condamine [12].

The Juandah and Taroom coal seams are comprised of coals that are sedimentary and formed

through the decomposition of organic material, which has been buried over time and

subjected to pressure and high temperatures [28]. It has been shown that the coal can

contain up to 125 different minerals dependent upon the specific environment in which the

coal was laid down, the environment in which the maturation process of the coal took place

and the transport of minerals through and around the coal by wind and water over time [28].

The mineral matter of coal can have an effect on the mineral matter of the aquifers

surrounding them through dissolution [28]. Coal can go through up to six stages of formation

which includes peat, lignite, sub-bituminous, bituminous, anthracite and graphite stages [28].

The Walloon Coal Measures are in the sub-bituminous to bituminous phase of formation [10],

according to classifications based upon colour, moisture content, heat content and density

[29].

CSG is generated by the decomposition of organic matter by anaerobic microorganisms [13].

It is formed within the pore space of the coal during the first stage of decomposition, namely

formation of peat [13]. The microorganisms metabolise organic matter by oxidation-

reduction reactions as this provides them with energy for growth and maintenance [13]. The

redox reaction of CSG involves the oxidation of CSG by oxygen (O2) to carbon dioxide (CO2),

while the oxygen is reduced to water [13]. CSG generation is governed by five important

criteria: anoxic environments, sulfate deficient environments, temperature, presence of

organic matter, and space [13]. The processes of aerobic respiration and subsequent

consumption of oxygen, sulfate reduction and anaerobic oxidation of organic matter

additionally contributes to the production of CSG [13]. While CSG formation in marine

sediments is created primarily via CO2 reduction, which occurs during the anaerobic oxidation


© 2016 Page 12

of organic matter, it has been suggested that there is no influence by marine sediments on

interior basins, which are those that are greater than 200-300 km from the ocean [10, 13,

30]. These non-marine influenced basins may be entirely fluvial and therefore the

recognition of sequence boundaries is more complicated to understand [30, 31]. It is

estimated that the Jurassic coast was more than 300 km from the eastern edge of the Surat

Basin suggesting that it is classified as an interior basin [30].

WATER CATCHMENT AND AQUIFERS

The Surat Basin has been used primarily for irrigated agriculture since the 1960’s [32]. The

Condamine-Balonne River is one of the major catchment areas within the Surat Basin and it

is the head of Australia’s Murray Darling River system [33].

Figure 1 (c): Condamine-Balonne River Catchment (Source:

http://155.187.2.69/water/policy-programs/entitlement-

purchasing/condaminebalonne.html)

The Condamine-Balonne River is used as a water resource for not only irrigated agriculture

through the development of three main irrigation projects but also for the domestic supply


© 2016 Page 13

of water [32]. The Upper Condamine irrigation project encompasses 196 km of the

Condamine-Balonne River followed by the Chinchilla Weir irrigation project which is situated

in the middle of the catchment and extends 88 km. The St George irrigation area is situated

at the lower end of the Condamine-Balonne River and has a length of 140 km [32]. Domestic

water storage is located at Leslie Dam, Chinchilla Weir, Beardmore Dam, and Jack Taylor Weir

which are located from the upper to the lower part of the catchment respectively [32]. The

Condamine-Balonne River passes through numerous private lands and may also contain

water storage within these areas [32]. The Condamine-Balonne River has a catchment area

of 143,900 km2 and receives a large input of water, but flows for most of its length across a

dry interior [32]. Freshwater can infiltrate through the coal aquifer, which can impact on the

quality of water and may result in the dissolution of minerals causing increased

concentrations of different chemical species [5]. The catchment of the Condamine Alluvium

within the Surat Basin can have highly variable rainfall patterns, experiencing periodical high

intensity rain and extended periods of drought [32, 33]. Most rainfall occurs in the summer

months, decreasing from east to west across the catchment, and is associated with tropical

monsoonal activity [32]. Consequently, average stream flow in the Condamine-Balonne

catchment is highly variable and all streams are ephemeral [34].

During periods of low rainfall, irrigated agriculture in the Surat Basin is dependent on

groundwater which is extracted from the Condamine Alluvium groundwater system [33].

Approximately 90 % of the water taken from the Condamine Alluvium, between 2005 and

2006, was for the irrigation of crops [33]. It has been found that there has been a decline in

the standing water level of the Central Condamine Alluvium from 1960 to 2008 [33]. The use

of the Condamine Alluvium by various industries highlights the importance of appropriate

management of water extraction during CSG operations.

The confined aquifers of the Surat basin are comprised of sandstone, which are separated by

mudstone and siltstone units [26]. The mudstone and siltstone are the confining beds and

recharge can only occur in the northern and eastern zones of the geological sequence [26].

This zone is in close proximity to the outcrop and the units are exposed sufficiently to allow

this to occur [26]. The sequence of the Condamine Alluvium consists of unconfined and semi-

confined aquifers [33]. Historical groundwater resources have been reliant upon the

Condamine Alluvium [35], however, these are mostly confined to the Central Condamine

Alluvium within the upper aquifers [33]. The Condamine-Balonne River can be characterised

by four distinct zones which operate under varied hydrological behaviour [32]. They are the


© 2016 Page 14

armoured, mobile, meandering, and the anabranch zones [32]. The armoured zone is an

immobile bed sediment with minimal movement in a floodplain environment, the mobile

zone is an active riverbed and channel, the meandering zone is an extensive floodplain with

sand channels, and the anabranch is characterised by multiple channels and a floodplain

system [32].

Hydrological processes operate at various time scales and geographic scales and as such the

complexity of the hydrology of the Condamine-Balonne River and the Condamine Alluvium

is extensive [32]. Factors such as formation and weathering processes acting on aquifers of

the Walloon Coal Measures are inherently varied. The geological contact between the

Walloon Coal Measures and the Condamine Alluvium is also a difficult system to identify as

the sediments are similar and geological logs are problematic to analyse [26]. The influence

of sea level change has in contrast been found to be negligible on the Surat Basin due to it

being classified as an interior basin [30].

EXTRACTION AND PRODUCTION OF COAL SEAM GAS

The CSG industry in Queensland is relatively new, and therefore there is some

unpredictability in the placement of exploration and production wells [3]. Often the amount

of water that is required to be extracted can also help to indicate the potential for production

performance [3]. A good producing well is classified as having a large gas reservoir,

saturation and permeability [3]. However, all three parameters cannot always be obtained.

A number of stages are required prior to CSG being removed: collection of seismic data,

analysis of core holes, and the development of exploration wells followed by production

fields with numerous wells.

Seismic data is used widely in the oil and gas industry and is a form of investigation to obtain

specific geological information [8, 36, 37]. Seismic data is obtained by the generation of

seismic waves that travel through the earth, which are either reflected or refracted, and

received back at the earth surface over a specified time period [8, 36, 37]. Using this gathered

information 2D, 3D or 4D pictures of the subsurface of the earth can be created [8, 36, 37].

Seismic data is used to obtain geological information during the exploration phase of the CSG

process in order to determine the geological strata including location, depth and thickness of

a coal seam prior to any drilling taking place.


© 2016 Page 15

Further investigation into the location of the potential coal seams is obtained by drilling a

core hole into the coal seam from the surface ranging in depth from 200 – 800 m for the

Walloon Subgroup. The core hole is approximately 10 – 30 cm in diameter and exposes the

rock and coal seam to allow for assessment [8]. The core hole provides information about

the amount of gas content, permeability of the geological strata, and thickness of the coal

seam [8]. Once the core hole is assessed, exploration wells are required to determine the

viability of a particular production field. Exploration wells in the Surat Basin consist of a

number of wells in a potential location, which are observed over time and are assessed based

on water and gas content. A large amount of water is initially extracted to enable the start

of gas removal from the coal seam [8, 38]. The pressure of each well is a determining factor

in how much water must be extracted prior to the gas being released [8]. During the process

of exploration the well will be dewatered and degassed until it is depleted. The gas produced

during the exploration phase is normally not used for power generation, but instead is cold

or hot vented to the atmosphere and this is undertaken due to legislative requirements by

the Queensland Government under the Petroleum and Gas (Production and Safety) Act 2004

which states that exploration activity cannot be used for power generation. The years that

it takes to dewater and degas the exploration well will show the potential for the wells

productivity.

Once CSG reserves are assessed using seismic data, core holes and exploration wells, it may

be classed as economically viable for gas production. Drilling of numerous wells in close

proximity to each other is necessary to extract CSG during the production phase [8]. The

infrastructure within the well consists of a drill head in the deepest part of the well and casing

which changes from conductor, surface, intermediate to production casing from the surface

to the gas reservoir [8]. The casing has alternate open and closed spaces through the

geological sequence, which corresponds to areas of coal seams [39]. The surface

infrastructure of the well includes a well head, power source, pump and pipelines [8]. CSG is

extracted and sent to a gas processing facility, which operates to dehydrate the gas and

compress it to extreme levels, which allows for the gas to yield the most energy when used

for power generation [8]. The CS water is moved to holding ponds where it awaits use and/or

treatment by various methods [40]. The final stage is for CSG to be used in an existing power

station or to be transferred to another processing facility to change the CSG to liquid, which

enables it to be exported overseas. CSG in Queensland is either sold into the national and

domestic electricity markets or to overseas markets as LNG [2]. In order for CSG to be

exported as LNG it is first transported by high-pressure pipelines to Curtis Island located off


© 2016 Page 16

the coast of Eastern Australia approximately 470 km north west of Brisbane [8]. Three

separate plants will be built on the Island to undertake this process with each being operated

by a different CSG operating company; QGC, Origin Energy and Santos [8]. The primary

application of the plant is to cool the CSG to the point at which it becomes liquid

(approximately minus 160°C) [8]. The LNG is transported by ship from Curtis Island to

countries such as China, Singapore, Japan and Chile [8]. The future of the Australian CSG

industry is to export overseas with approximately 24 million tonnes of LNG being exported

during 2013-14 with a revenue of $16.4 billion Australian dollars [2, 8].

CSG is trapped within a coal seam by the pressure of an aquifer which surrounds it and can

only be released by partial dewatering [4]. The geological profile can have impermeable

layers e.g. clay above and below the coal seam and this also contributes to the ability of the

coal seam to trap CSG [38]. Mining of CSG in the Surat Basin involves drilling of vertical and/or

lateral wells from the surface to depths of between 200 and 800 m to within the coal seam

[10]. During the drilling process of a CSG well, a two layer steel casing is inserted as the hole

is drilled. The steel casing is surrounded by cement to maintain exclusion of the drilled well

from the overlying and adjacent geology including aquifers [8, 41]. In the Surat Basin, the

extraction process of CSG from the coal seam generates a substantial amount of CS water

[7]. CSG is held within the spaces of the coal seam by the pressure of the aquifer [5]. As the

water is released by mechanical methods and the pressure drops, the gas is also released.

The deeper the coal seam the higher the pressures acting on the seam [5].

During the extraction of CSG varying amounts of CS water will be produced from each well

[4, 38, 42]. This is a consequence of the amount of pressure that is acting on the coal seam,

and over time the amount of water will decrease and the amount of CSG extracted will

increase until the CSG is depleted [42]. The production fields can range in not only size but

also the number of production wells in each field. An example is the comparison of the 600

production wells drilled in Queensland in 2010-11, and the Powder River basin in Wyoming

and Montana in the US which has 16,000 wells under production [4, 43].

LEGISLATIVE AND RE-USE OPTIONS OF CS WATER

CS water has a particular chemical composition based on the location from which it is

extracted, however, there are some similarities between CS water at great distances from

each other [42]. Similarities exist for CS waters from New Zealand, the US and Australia and

include high bicarbonate (HCO3-) high sodium (Na+), high chloride (Cl-), low calcium (Ca2+), low


© 2016 Page 17

magnesium (Mg2+) and low sulfate (SO42-) concentrations [1, 5, 38, 42, 44]. CS water from

the Juandah and Taroom coal measures are generally characterised as brackish water

consisting of primarily high salt content (200 – 10,000 mg/L) and high bicarbonate content

(1000 mg/L) [34]. Other parameters that are characteristic of CS water from New Zealand,

the US and Australia are high sodium adsorption ratio (SAR), high total dissolved solids (TDS)

and high alkalinity [1, 38, 44]. Although similarities exist, it has been noted that variation in

chemical composition can exist between samples taken from a single well over time and can

be due to factors such as pressure loss when the CS water is brought to the surface,

interaction of the CS water with the atmosphere or temperature at the surface [38].

Legislative Requirements

There is potential for CS water to impact the environment if it is released to land or to surface

waters untreated [43-46]. Concentration limits for water quality parameters are set to

maintain a minimum impact upon the natural environment such as soils, vegetation and river

systems. The plant and equipment associated with a particular industry is also considered in

relation to the health of fauna species. Therefore, the Australian Government, through State

legislation, regulates the use and discharge of CS water for all companies that operate

exploration and production CSG wells within the Surat Basin. The CS water is regulated by

the Environment Protection Act 1994, for physical and chemical parameters, and the

concentrations required are dependent on the application in which the CS water is to be used

[47]. Currently, CS water from the Surat Basin is legislated to be used for livestock watering,

irrigation, coal washing, aquaculture, industrial and manufacturing operations, drinking

water, and domestic purposes for landowners within petroleum tenure [48]. CSG operating

companies are permitted to use CS water for drilling operations and construction purposes

e.g. dust suppression [47]. Two permit types exist to regulate the use of CS water for

particular activities: Environmental Authority and beneficial use approval. The

Environmental Authority is used when a CSG operating company is using the CS water for

CSG related activities such as drilling, dust suppression or construction. The beneficial use

approval is used to stipulate conditions that are required to be met prior to the CS water

being used by other industries not related to CSG production or operation. This process is

administered in Queensland by the Department of Environment and Heritage Protection

(DEHP) [47, 48].

Beneficial use approval contains specific physical and chemical water quality parameters to

be met for every CSG operating company. On the other hand, the Environmental Authority


© 2016 Page 18

is specific to petroleum tenure, with each CSG operating company working under multiple

petroleum tenures. A petroleum tenure is a parcel of land that is no more than

approximately 210 km2 and entitles the holder to explore, produce and process petroleum

and gas and must be applied for through the Queensland Government [49]. Consequently,

companies face the prospect of dealing with many Environmental Authorities due to working

in many petroleum tenures. At this time there are 33 Environmental Authorities current in

the Surat Basin [47]. Table 1 shows the physical and chemical limits for each industry that is

able to use CS water in the Surat Basin [47]. Tables 2-5 detail each Environmental Authority

and the physical and chemical limits that allow CSG operating companies to use CS water for

construction purposes and drilling operations. Tables 2-5 show that the water quality

specifications vary between Environmental Authorities for each CSG operating company, for

the same application, around parameters such as pH, TDS, EC, TPH, SAR and bicarbonate ion

content. There are two companies, QGC and Origin Energy that have six Environmental

Authorities that include 20 other parameters that are required to be tested prior to the CS

water being used for hydrostatic testing or low point drain release and this is described in

Table 2. This shows that the hydrostatic testing and low point drain application are subject

to different conditions depending on the CSG company, with QGC and Origin Energy having

a larger testing suite than Arrow Energy or Santos.


© 2016 Page 19

Table 1: Beneficial Use Approval Water Quality Requirements for Reuse of CS water in the Surat Basin

Use [48] Requirements of the Producer Requirements of the User

Aquaculture Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC & ARMCANZ)

ANZECC & ARMCANZ

Landscape and Revegetation TDS 1000mg/L

pH 6 – 9.5 −

Domestic, Stock, Stock Intensive and Incidental Land Management

ANZECC & ARMCANZ ANZECC & ARMCANZ

Table 2: QGC Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin

Reference Number [47]

Last Revised

Company Purpose pH TDS mg/L TSS mg/L EC μs/cm TPH mg/L SAR Bicarbonate

Ion mg/L

EPPG00611313 2014 QGC

Origin

Construction, Dust,

Industrial, Manufacturing

6 – 9.5 1000 − − − − −

EPPG00652513 2015 QGC

Drilling, Simulation,

Dust, Construction,

Industrial, Manufacturing, Coal Washing, Landscaping, Revegetation

6 – 9.5 1000 − − − − −

EPPG00932613 2014 QGC Hydrostatic

Test * 6.5 – 8.5 − − 2000 10 8 – 12 −

Dust 6 - 9 2000 − − 10 8 – 12 −


© 2016 Page 20


Last Revised


Ion mg/L EPPG00797813 2014 QGC Dust 6 - 9 3000 30 − 100 8 - 15 100 EPPG00878413 2014 QGC Construction − − − − − − −

Landscaping, Revegetation

6 - 9 1000 − − − − −

Industrial,

Manufacturing 6 – 9.5 − − − − − −

EPPG00889613 2014 QGC Dust,

Construction − − − − − − −


6 – 9.5 100 − − − − −

Industrial,

Manufacturing 6 – 9.5 − − − − − −

Livestock ANZECC & ARMCANZ

EPPG00903513 2014 QGC Dust,

Construction − − − − − − −


6 – 9.5 1000 − − − − −

Industrial,

Manufacturing 6 – 9.5 − − − − − −


* Testing requirements also include the following: Na, Ar, Se, B, Cd, Cr, Cu, Pb, Fe, Mn, Zn, N, P, Hg, F, Al, Ni, Ag, V


© 2016 Page 21

Table 3: Origin Energy Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin


Last Revised


Ion mg/L

EPPG00304413 2014 Origin − − − − − − − −

EPPG00300013 2014 Origin − − −

EPPG00611313 2014 QGC

Origin

Construction, Dust,

Industrial, Manufacturing

6 – 9.5 1000 − − − − −

EPPG00653413 2015 Origin Construction 6 -9 2000 − − 10 − −

Hydrostatic Test*

6.5 – 8.5 − − 2000 − − −

EPPG00853013 2014 Origin Hydrostatic

Test* 6.5 – 8.5 − − 2000 − − −


Test* 6.5 – 8.5 − − 2000 − − −


Test, Low Point Drain*

6.5 – 8.5 − − 2900 10 − −


Test* 6.5 – 8.5 − − 2000 − − −

* Testing requirements also include the following: Cl, Ar, Se, B, Cd, Cr, Cu, Pb, Fe, Mn, Zn, N, P, Hg, F, Al, Ni, Ag, V


© 2016 Page 22

Table 4: Arrow Energy Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin

Reference Number [47] Last Revised Company Purpose pH TDS mg/L TSS

mg/L EC μs/cm

TPH mg/L

SAR Bicarbonate

Ion mg/L EPPG00653213 2013 Arrow Dust 6 – 9 2000 30 − 10 − −

EPPG00972513

2014 Arrow Dust,

Construction, Operation

6 – 9 1500 − − 10 6 - 12 −

PEN100251408 PEN200405209 PEN200528910 PEN201259310

2011 2010 2011 2011

Arrow No requirements for water quality parameters

Table 5: Santos Environmental Authority Water Quality Requirements for Petroleum Lease Tenure in the Surat Basin

Reference Number [47] Last Revised Company Purpose pH TDS mg/L TSS

mg/L EC μs/cm

TPH mg/L

SAR Bicarbonate

Ion mg/L EPPG00892413 EPPG00898213 EPPG00928713 EPPG00980113 PEN100395309 PEN100395409 PEN100401209 PEN200748210 PEN200748310 PEN200767410 PEN201029710 PEN201644210 PEN202693011

2010 - 2015 Santos

Dust, Construction, Hydrostatic Test, Low

Point Drains

No requirements for water quality parameters



© 2016 Page 23

The difference between the Environmental Authority for the same water quality parameters

and the same applications is of significance. It has been shown in other studies worldwide

that there may be regional differences of large or small scales in CS water and this may or

may not correspond to the differences in concentration limits for the water quality

parameters in the Queensland legislation through the Environmental Authority [1, 5, 38, 42,

44, 50]. CSG operating companies through water quality monitoring programs may be able

to provide region specific water quality data. As a consequence, this information may enable

the Environmental Authorities to better address particular CS water types, which in turn

could promote more effective and efficient use.

Beneficial Re-Use of CS Water

There are several different re-use methods that CSG operating companies have identified

and are currently undertaking for CS water. Re-use strategies can be separated into those

undertaken by the company themselves or the transfer of the CS water to external industries.

When the CSG operating companies use CS water in their own business, this is undertaken

mostly during the construction of gas related infrastructure and also during the drilling of

exploration and/or production wells [47].

Agriculture

The Surat Basin has an economic stake in the production of meat cattle and intensive farming

such as feedlots [15]. The requirements for cattle drinking water as outlined by the

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC &

ARMCANZ) illustrates a range of criteria which need to be satisfied, including TDS <5000

mg/L, fluoride <2 mg/L, boron <5 mg/L, chloride <2000 mg/L, and aluminum <5 mg/L [51].

At the low end of the salinity range CS water can be used directly as stock drinking water

which is currently being undertaken in the Surat Basin for cattle feedlots without any

treatment needed to improve water quality. Alternatively, mixing CS water with potable

water may be necessary to ensure all water parameters are compliant to concentration levels

in accordance with the ANZECC and ARMCANZ.

Irrigation

Irrigation for cropping farms is also a significant economic resource in the Surat Basin and

water security is a major part of this industry [15]. CS water is now being used as part of the

current water schemes (the process of delivering water through infrastructure) and an

example of this is the Chinchilla Weir water scheme in which CS water is being transferred


© 2016 Page 24

[52]. The Chinchilla Weir is used both for irrigation along the Condamine River and also to

enhance the water supply to the townships of Chinchilla and Toowoomba [52]. The crops

irrigated using the Chinchilla Weir include cereal, melons, pasture and fodder crops [52]. Up

to 85 ML/day can be treated and transported to the Chinchilla Weir [52]. The supply storage

of the Chinchilla Weir is 9780ML and in 2008-09 approximately 3000 – 3500 ML was used

[52]. CS water salinity can have a variable range and therefore it is important to understand

not only salinity range for CS water but also crop salt tolerance levels [53]. This is typically

assessed by calculating SAR:

SAR = Na+

√12

(Ca2+ + Mg2+)

A major problem of CS water for use as irrigation water in the Surat Basin is the parameter

SAR, which can increase sodicity in soils, leading to the soils inability to form stable

aggregates and thus structure [53].

Dust Suppression

During the construction of any infrastructure, the requirement to remove vegetation and

topsoil is essential, which results in exposure of the subsoil. The CSG industry in Queensland

must not only drill CSG production wells but other infrastructure must be built such as water

treatment plants, water holding dams, gas compression facilities, offices, mining camps and

more. Nuisance or environmental harm can be caused by dust due to displacement and

deposition in locations such as creeks and rivers or landowners houses. This behaviour

occurs during the time when the subsoil is exposed and subjected to wind movement. The

most common method to alleviate this problem is through the application of a thin layer of

water to the areas that are susceptible [47, 48]. The CSG industry is currently using CS water

for this application, in some cases CS water can be used directly for dust suppression without

any treatment, however companies must adhere to legislative requirements which means

that treatment may be required prior to use [47].

Drilling Activities

CSG operating companies also require water when undertaking drilling activities specifically

for addition to drilling fluid which can be made up of a combination of CS water, sand, acetic

acid, caustic soda, calcium chloride, guar, and/or potassium chloride [8, 54]. Fracturing fluid

chemistry takes in to account the geological characteristics of the location being drilled and

the chemical characteristics of the aquifers involved with the drilling process [55]. The drilling


© 2016 Page 25

fluid is used down the hole to cool the drill bit or prevent destabilisation of the hole [8]. The

drilling fluid is subsequently mixed with the cuttings removed from the hole and this is

separated above ground with the separated fluid potentially being returned down the hole

for reuse as drilling fluid. However in some cases, the fluid is not able to be used for this

application and must be disposed of [8].

Hydrostatic Testing and Low Point Drains

Pipelines constructed to transfer gas and water from the production well to other

infrastructure such as gas compression facilities or water holding dams are called gathering

systems. These pipes typically require testing prior to use to ensure that they can withstand

design pressure and are safe for operation [56, 57]. This process involves hydrostatic testing

and in the CSG industry it is undertaken using CS water. The CS water must be released

periodically along the length of the pipeline through high point vents where only small

amounts of water are released. In some instances, release may occur from the pipeline itself

and or be released to the ground. Therefore, the concentration level of the CS water should

adhere to the legislative requirements set out in the Environmental Authority [47, 56, 57].

Another requirement of pipelines associated with CSG transfer is known as low point drains,

which are installed at set locations along the pipeline in the low points of the topography.

The provision of drains is required as the CSG is saturated as it is in contact with CS water in

the well and at any surface separator. The gas becomes supersaturated as the gas cools

through the gathering system, condensing and accumulating at the low points of the pipeline

and must be released [56, 57]. Low point drain release is subject to similar legislative

requirements as hydrostatic testing [56, 57].

Managed Aquifer Recharge

Managed aquifer recharge of CS water has been undertaken in countries such as the US and

has been found to be a successful management tool [58, 59]. This technique is used if the CS

water is not required for any other re-use method and is a way to not only alleviate storage

space required for large amounts of CS water but also to comply with Australian Government

Federal legislation. In Australia managed aquifer recharge is being tried by some of the CSG

operating companies in the Surat Basin [60, 61]. Although being a convenient way to dispose

of CS water and allowing for the protection of depleting an aquifer, it is essential that the

water re-injected protects the ecology of the aquifer. Key points to consider include pH

adjustment, deoxygenating, and sterilisation (removal of solids and bacteria) of the CS water

prior to reinjection [60]. Reinjection wells are drilled to the precipice sandstone aquifer


© 2016 Page 26

(approximately 1500 m), the Hutton sandstone aquifer (approximately 680 m), or an aquifer

that avoids interconnectivity with the coal seam being exploited. This could be any aquifer

above or below the coal seams which are being exploited for CSG [60]. pH adjustment is

necessary to ensure that water returned to the aquifer resembles the chemical composition

of the water that is already present, and also to ensure minimal environmental impact to

aquifer occurs, such as preventing the precipitation of minerals [60]. The pH of CS water is

normally reduced by hydrochloric acid reinjection [60]. The presence of oxygen can cause

deterioration of the steel casing of the well [60, 61]. Equally problematic is the dissolution

(and / or oxidation) of precipitated species and subsequent mobilisation [60]. Removal of

oxygen, using hydrophobic gas transfer membranes or alternative technology, is required as

the water present in the sandstone aquifers typically has a dissolved oxygen content that is

very low (less than 10 μg/L) [60]. Sterilisation is undertaken in order to kill bacteria present

in the CS water, with ultraviolet disinfection conveniently used [60]. In the US as much as

100 ML per day of CS water can be re-injected, however in Australia current trials average

between 10 to 50ML per day [60].

DEHP is continually reviewing the way in which the CSG industry in Queensland regulates

water quality by reviewing conditions within the Environmental Authority and beneficial use

approval periodically [47, 48]. Conditions that may be revised include physical and chemical

parameters that govern the way in which the CS water can be used. Through the appropriate

management of water quality within environmental permits in the CSG industry the risk of

water shortage in Australia can be significantly reduced. Due to the variable nature of CS

water, consistent monitoring programs for the duration of CSG extraction may be required

to ensure that specific water quality information is being assessed and included in

environmental permits. This will enable CSG operating companies to use the most cost

effective and efficient treatment technologies and therefore CS water can be used as a

valuable resource.

TREATMENT TECHNOLOGIES

The composition of untreated CS water may render it unsuitable for large scale beneficial use

therefore it may be necessary for a treatment method to be implemented. The treatment

methods for CS water vary and are dependent upon regulations, cost, time and application.

Each beneficial use application requires a specific quality of water, which means a number of

pretreatment, principal treatment and post treatment systems may be required to satisfy all

regulatory measures [47, 48]. As the CS water quality is not consistent, a range of treatment


© 2016 Page 27

methods may be used by each CSG operating company and indeed can be different

depending upon which region of the Surat Basin is involved.

Pre-treatment

Pre-treatment of CS water is necessary to protect the principal treatment method from

fouling of the filters and reducing the efficiency [62]. This is necessary as the principal

treatment technology is normally the more expensive treatment both in terms of cost to set

up and ongoing maintenance cost. The most common objective of pre-treatment, (including

holding dams, filtration and chemical amendment) is to remove fine / coarse solids and

bacteria / algae to improve efficiency of the principal treatment technology and prevent

fouling of the membranes [62]. Holding dams are used to store CS water prior to treatment

and they reduce sediment over time by settling processes. The CS water stored in holding

dams most commonly use coarse sediment filters when the water is transferred for

treatment and this is undertaken to remove solids. The dams can vary in size, with current

basin sizes in the Surat Basin ranging from 10 to 160 ML [61, 62]. The holding times for CS

water within the holding dams is based on the amount of input from CSG production wells

and the amount of water that can be treated per day by the principal treatment technologies

[61, 62]. Further pre-treatment methods that are used by the CSG operating companies in

the Surat Basin include either micro-filtration or ultrafiltration. These techniques are a

separation process that involve passing water through a specific pore size filter and high

velocity and low pressure [62]. The filters can range from 0.1 – 10 μm for micro-filtration

and 0.1 - 0.001 μm for ultrafiltration. This process typically restricts coarse sediment, algae,

bacteria and other microorganisms [62]. RO is the major technology selected to treat CS

water so that it is of a quality specified by government regulatory agencies, and therefore

able to be beneficially used [40, 63].

Principal Treatment

The principal treatment method used by all CSG operating companies in the Surat Basin is

RO, which reduces many water parameters simultaneously [44]. RO is a system based on the

application of sufficient pressure to semi-permeable membranes and the ability of the

membrane to separate particles or dissolved matter nearly completely from water [62, 64,

65]. The output is classified into two water types; permeate and the concentrated salt

solution termed brine [62, 64]. The chemical composition of the permeate is of high quality,

with heavy metals, SAR, TDS, EC, HCO3-, and Na+ removed [62, 66]. An advantage of the RO


© 2016 Page 28

system is that it can typically recover between 75-80% of the water as permeate depending

on the type of membranes that are used and the type of water that is input into the RO

system [62, 67]. The membranes work by moving the water across different pressures, which

is permeable for water only [62, 65]. A major component of the maintenance of the RO

equipment includes dosing the water with chemicals prior to treatment in order to prevent

scaling and fouling [62, 68, 69]. Fouling is caused by a number of different species such as

high contents of suspended solids, salt, calcium, magnesium, silica, boron and organics [62,

68, 69].

Ion exchange is a technique that is commonly used as a water treatment technology for the

removal of alkali metal and alkaline earth ions [70, 71]. In the US, ion exchange has been

used as the principal desalination technology for CS water [72]. However, in Queensland the

main area of interest for ion exchange application is water softening (removal of alkaline

earth ions – Mg and Ca) [73]. The process involves the removal of alkaline earth ions from

the solution by the introduction of a polymeric resin [74]. This has been found to be

successful in reducing contaminants in water and therefore protecting the RO membranes if

ion exchange is used prior to RO treatment [75].

Post Treatment

The amendment process is a post treatment technology that incorporates the change of

concentration of a particular element after the principal treatment technology has been

undertaken [76]. Permeate water can be treated with CaCl2, re-mineralised, re-hardened, or

disinfected by chlorination during the post treatment phase [62]. Another post treatment

method is lime dosing (addition of lime powder or liquid to the CS water) which is undertaken

to specifically increase Ca2+ in water prior to the water being used for irrigation purposes

[45]. CaCl2 is another amendment process that is used to decrease SAR specifically when the

water is going to be used on the ground. The amendment of SAR is of particular importance

for due to the negative impact that Na+ has on soil [45]. An increased concentration of Na or

high SAR can result in the inability of soil to uptake water and increases the soils breakdown

of chemical bonds and thus structure and susceptibility to subsequent erosion [77, 78].

Table 6 shows the major CSG operating companies in the Surat Basin, Arrow Energy, QGC,

Origin Energy and Santos and the treatment technologies that are currently utilised to treat

CS water. This shows that RO water treatment plants with input from retention dams is the

principal treatment technology for all companies. The amount of water being treated is


© 2016 Page 29

varied and could be due to the location and/or the number of CSG production wells i.e. area

being used. Pretreatment and post treatments are varied between CSG operating companies

as treatment is dependent on the water re-use strategy that is in place and the quality of

water to be treated.


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Table 6: CS Water Treatment Infrastructure in the Surat Basin for Major CSG Operating Companies

Company Pre-Treatment Principal

Treatment Post Treatment Location Water Treated Reference

Arrow Energy Retention Basin Microfiltration

Reverse Osmosis CaCl2 Dalby – 2 sites 2.5ML/day [79, 80]

QGC Retention Basin Ultra Filtration Disc Filtration

Ion Exchange Reverse Osmosis

Lime Dosing Chinchilla Wandoan

92ML/day [81]

Origin Energy Microsand Ballasted

Flocculation Reverse Osmosis −

Roma Chinchilla

20ML/day [54, 82, 83]

Santos Microsand Ballasted

Flocculation Reverse Osmosis −

Roma Fairview

10ML/day 20ML/day

[76, 81, 82]

Santos −

CS water Amendment Facility using

H2SO4 & CaSO4

− Roma 20ML/day [84]


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Each CSG operating company has designed the CS water treatment technologies in different

ways and with the capacity to treat varied amounts of water. The amount of water requiring

treatment is also directly proportional to the number of production wells that are operating.

Therefore, the water treatment facilities developed by each company must anticipate the

CSG production wells that will be drilled for the duration of the CSG extraction. Not only

does the amount of water need to be taken into consideration but also the major beneficial

use applications. If a significant proportion of the treated CS water is to be used for a specific

purpose then specific principal and post treatments may be required.

DESALINATION TECHNOLOGIES

The water quality of the associated or produced coal seam (CS) water is highly

variable but as a general observation is in the brackish water range (500 to 10,000

mg/L) in Australia, but can be of higher total dissolved solids (TDS) values in other

countries such as the USA [18]. The major dissolved salts present are sodium chloride

and sodium bicarbonate, along with concentrations of alkaline earth ions (Ca2+, Mg2+,

Ba2+ & Sr2+), potassium, sulphate and other minor species (iron, aluminium,

ammonium) bicarbonate [6, 16, 85]. In many cases CS water requires treatment prior

to beneficial reuse due being incompatible with regulations for irrigation, stock

watering and drinking water as examples [86].

Desalination technologies such as reverse osmosis (RO) have been deployed as they

are a proven and robust process for production of high purity water [6, 7, 67, 74]. As

such, electricity costs can be relatively expensive as can be the number of pre-

treatment methods employed to ensure that RO achieves acceptable water recovery

rates [7, 87]. Pre-treatment methods prior to the RO membranes include but are not

limited to lime softening, coagulation, microfiltration, ultrafiltration, anti-scalants, pH

adjustment, ion exchange softening [86]. The objective of the pre-treatment stages

is to reduce the incidence of fouling of equipment and membranes by species such

as organic material [88], scale forming species such as calcium carbonate [89] and

silicates [90]. Scaling occurs when salts are concentrated within the element beyond

their solubility limit [91]. The most common of these salts are CaSO4, CaCO3, and


© 2016 Page 32

silica [92]. The direct reduction of these salts presence prior to introduction of the

CS water into the system will reduce scaling of the RO membranes [91, 92].

The inherent variability of CS water composition poses a challenge for consistent

operation of RO plants. This study investigated the CS water composition from 150

wells located in the Surat Basin in Queensland, Australia (the results of which have

recently been published [93]). It was found that even in the same region of a CSG

basin that the water composition ranged not only in the amount of total dissolved

solids but also the quantity of scale forming species such as alkaline earth ions and

dissolved silicates. CS water contained up to 3700 mg/L sodium ions, 5910 mg/L

chloride ions and 2030 mg/L bicarbonate ions. Notably, calcium ion concentrations

could spike in intensity from values usually below 20 mg/L to in excess of 100 mg/L.

Similarly, magnesium ions were recorded to range from 1 to 34 mg/L and silica from

13.8 to 23.1 mg/L. A key conclusion was that the different CS water compositions

may cause problems when desalinated using reverse osmosis as the scaling potential

may promote membrane fouling.

At present in the literature there is information about CS water compositions, plus an

indication that reverse osmosis technology is used to desalinate CS water but not a

basis for design of suitable RO systems complete with pre-treatment stages.

Consequently, a methodology is required to predict what the configuration and

operating conditions of a suitable reverse osmosis desalination plant should be.

Several authors have used computational methods to simulate performance of

various membranes for a range of water compositions ranging from brackish to

seawater types. Alhadidi et al. [94] used the software package IMS design supplied

by Hydranautics to evaluate the scaling behaviour of species such as barium sulphate,

calcium sulphate, strontium sulphate, silica and calcium carbonate from canal; water

when being treated by a reverse osmosis unit. The resultant data allowed the plant

operator to reduce the demand for anti-scalant use and to predict the required

operating pH of the water to minimise precipitation of scale forming species.

Poovanaesvaran et al. [95] applied Reverse Osmosis System Analysis (ROSA) software

from Filmtec to examine reverse osmosis plant configurations for treating brackish


© 2016 Page 33

water and concluded a two stage system was preferable to a single stage process due

to a lesser total energy consumption. Aghdam et al. [96] also applied ROSA software

to predict the scaling potential of brines produced from treatment of Central Arizona

Project water by a nanofiltration membrane. Altaee [97] extensively used ROSA

software to examine whether end feed or central feed designs for RO pressure

vessels were preferable. End feed designs were found to require less energy for

operation, however, they were more susceptible to issues with scaling. Several

authors have compared fundamental models they developed for reverse osmosis

systems with ROSA and found acceptable levels of agreement [98, 99].

SUMMARY

The CSG industry in Australia is of importance not only for domestic gas supply markets but

also for significant export potential as LNG. The environmental impact of CS water produced

during the extraction of CSG needs careful consideration with regards to the quantity and

quality of the water. There is no doubt that the CS water has the potential to benefit a range

of industries such as agricultural, mineral mining, manufacturing and aquaculture and should

be seen as a resource. The chemical composition of the water can be impacted by it’s

geological location and the depth at which it is found, and can be complex due to multiple

hydrological processes and aquifers which can interact with the coal seams. In most

instances, the CS water may require treatment prior to beneficial reuse. A number of

different water treatment strategies have been implemented in the Surat Basin by CSG

companies, and these have been selected according to factors such as the amount of CS

water that is to be treated and the way in which the CS water will be re-used (subject to

legislative requirements). The formation, extraction, and production of CSG as well as the

treatment of CS water including current requirements by the Queensland Government has

been outlined, and it has been shown that the legislative requirements are not consistent

between CSG operating companies. The appropriate selection of pre-treatment technologies

as well as RO membranes, based on the concentration of the water quality parameters, will

ensure that CS water can be treated to the point it is compliant with regulations provided by

the Queensland government and used for the most appropriate beneficial use applications.

IMPLICATIONS

This study focussed primarily on the Surat Basin located in Queensland and northern New

South Wales. The mechanism for CSG formation, relation to local geological features,


© 2016 Page 34

extraction approach and the potential impact/benefits of associated water have been

discussed. An outline of the current legislative requirements on physical and chemical

properties of associated water in the Surat Basin was also provided, as well as the current

treatment technologies used by the major CSG companies. This review was of significance in

relation to the formulation of the most appropriate and cost effective management of

associated water, while simultaneously preserving existing water resources and the

environment.

The aim of this study was to extensively analyse a large number of operating CSG wells in the

Surat basin, determine compositional variability and to interrogate physical relationships for

water within and between multiple gas fields. Specific objectives included the identification

of trends in water chemistry, related to depth, or location of the CSG production well in order

to provide information which could aid management of the CS water. Multivariate analysis

was employed to link parameters and to recognise patterns in the water data. From this

information, systematic identification of the most appropriate and economical means to

store and treat associated water may evolve based on location, depth and regional geology.

A predictive model will be discussed later in the thesis which concerns relation of total

dissolved solids and conductivity of CS water. Electrical conductivity of CS water can be easily

tested at the well head or management dam, and it will be shown later that this measure is

accurate enough to be practically useful for assessing water quality and aiding decision

making for water management.

The application of software tools such as ROSA and IMS Design can be used to aid in the

design of RO units which can operate over a wide range of CS water compositions and assess

their performance on changes in water quality. Consequently, this study was undertaken to

answer the following research questions: (1) Evaluate how variations in concentration and

composition of CS water impact RO performance; (2) What is the impact of membrane

selection upon desalination operation; (3) What are the scaling potentials which can be

expected for CS water compositions; (4) Which pre-treatment methods are recommended

to minimise fouling and scaling of RO membranes. This study used CS water compositions

which represented mean, minimum, and maximum concentrations of water in the Surat

Basin, Queensland. Water quality after RO was predicted and then compared with irrigation

guidelines.

Chapter 3: Research design

© 2016 Page 35

2Chapter 3: Research design

The methodology used in this study and the stages at which this methodology was

implemented is discussed. A list of all the instruments and analysis techniques used in the

study and the corresponding standards and guidelines is also outlined. The modelling

programs used to analyse the water quality have been described.

SITE SELECTION

CSG samples in this study are from the Surat Basin, Queensland, Australia. The Surat Basin is

a large interior basin of an area of approximately 300,000 km2 and extends (approximately

400 km in length) from Queensland to New South Wales [11]. The coal seams from which

the CSG is currently being sourced are the Walloon subgroup which include both the Juandah

and Taroom Coal Measures. The Walloon subgroup is located in the eastern section of the

Surat Basin, between Dalby, west to Roma and north to Wandoan [12]. Well site selection is

based on the CSG production wells that are in operation from the eastern Surat Basin during

July to September 2012 [Figure 2 (a)].

Figure 2 (a): Petroleum tenures in Condamine-Balonne area: Source;


© 2016 Page 36

http://www.bioregionalassessments.gov.au/assessments/12-resource-assessment-

maranoa-balonne-condamine-subregion/12322-proposed-csg-projects

SAMPLING PROGRAM

The sampling program involved the collection of CS water samples from 150 CSG production

wells that were in close proximity to each other, with the greatest distance between wells

being approximately 36 km and the least less than 1 km. The CSG production wells were

operational at the time of sampling. The CSG was being withdrawn from the coal seam and

being transferred to an existing CSG production facility for processing and delivery to a power

station. The water that holds the CSG at pressure in the coal seam is withdrawn and is

separated from the CSG at the production well and transferred to separate holding ponds.

The water samples in this study were taken from the CSG production well prior to the CS

water being transferred to the holding ponds, therefore no storage or treatment had

occurred at the time of sampling.

The method used to sample the water was the standard groundwater practice as described

by the DEHP, Monitoring and Sampling Manual 2009 and the Australia and New Zealand

Standards, Guidance on Sampling of Groundwater [100, 101]. The process of water

extraction is from a direct connection of PVC plastic tubing to the components of the CSG

production well from where the water could be sourced by way of a valve. Approximately 3

m length of plastic tubing was used to transfer the CS water to a plastic sampling bucket from

which the water sample was taken. In order to ensure that all residual water from the well

components was released prior to sampling being undertaken approximately 5 times the

volume of the length of the plastic tubing was purged. To reduce agitation of the water

during sampling a flow meter was used which trapped the CSG and allowed the water to pass

through to the sampling container. The CS water samples from site were collected in

accordance with Australian Standards and Australian Laboratory Services (ALS) collection

procedures and sample bottles [102, 103]. The water samples were transferred from the site

at which they were collected to ALS Brisbane laboratory for analysis, within 24 hours from

when the water sample was taken. Samples were kept chilled for preservation reasons prior

to the sample being analysed.


© 2016 Page 37

CHARACTERISATION TECHNIQUES

The CS water samples were analysed by ALS for a number of physical and chemical parameters

that were used to undertake this research project. Table 7 shows the parameters that have been

tested as part of this study.

Table 7: Parameters Tested for CS water in the Surat Basin

Parameter Units Abbreviation

pH pH units -

Sodium Absorption Ratio - SAR

Electrical Conductivity µS/cm EC

Total Dissolved Solids (field filtered to 0.45 µm) mg/L TDS

Total Suspended Solids mg/L TSS

Turbidity NTU -

Total Hardness as CaCO3 mg/L Hardness

Residual Alkali mg/L RA

Alkalinity species (total, bicarbonate, carbonate and

hydroxide) mg/L CaCO3

Total anions – bromide, carbonate, sulfate, chloride mg/L Br- Cl- SO42-

Total cations – dissolved calcium, magnesium, sodium,

potassium mg/L Ca2+ Mg2+ Na+ K+

Metals – total and dissolved (Aluminum, Arsenic,

Barium, Beryllium, Boron, Cadmium, Chromium (VI

and III), Cobalt, Copper, Iron (ferrous and ferric), Lead,

Manganese, Molybdenum, Nickel, Strontium,

Selenium, Vanadium, Zinc (ferrous and ferric) (field

filtered to 0.45µm)

mg/L

Al3+ Ar Ba Be B Cd

Cr Co Cu Fe+ Pb

Mn+ Mo Ni Sr Se V

Zn

Mercury mg/L Hg

Trivalent and Hexavalent Chromium mg/L Cr

Silica (soluble and reactive) mg/L SiO2

Fluoride mg/L F-

Total Ammonia as N mg/L _

Nitrogen species mg/L N

Phosphorus species mg/L P

Dissolved Organic Carbon (field filtered to 0.45 µm) mg/L DOC


© 2016 Page 38

Total Organic Carbon mg/L TOC

Physical Parameters

Electrical conductivity is measured by passing a current between two electrodes placed in

the water sample. It is the measure of the number of charged particles in the water and the

unit of measurement is micro Siemens per centimetre (μS/cm) or milli Siemens per

centimetre (mS/cm). Electrical conductivity indicates low nutrient and high salinity in water.

pH is a measure of the concentration of hydrogen ions and describes the acidity or alkalinity

of the sample. It is measured on a scale of 1 to 14 pH units with 1 being the most acidic and

14 being the most basic. pH is measured electrochemically using a glass electrode and a

reference electrode and it is calibrated with a three point buffer solution of pH 4, pH 7 and

pH 10.

Turbidity in water is a result of suspended or colloidal matter (organic or inorganic material)

and is a measure of the clarity of the water. Turbidity is measured by passing a light through

the water column and this is compared to the light scattered by a standard reference, it is

measured in nephelometric turbidity units (NTU).

Laboratory Tested Parameters

Total suspended solids are the total solids in the water sample that are of a measured pore

size, for this project this is >0.45 μm. The water sample is filtered, dried and the weight is

then measured in mg/L. Total dissolved solids is a measure of concentration of dissolved

solids in the water sample. TDS is measured in mg/L and can be determined by the

evaporation of water sample and weighing the material that remains (the dissolved solutes).

Sodium adsorption ratio has been calculated by a mathematical equation using the sodium,

calcium and magnesium ion concentrations determined by:

SAR = Na+

√12

(Ca2+ + Mg2+)

The measurement unit is a ratio.


© 2016 Page 39

Total hardness is a measure most predominately of the concentration of calcium and

magnesium ions in water and can be expressed as calcium carbonate (CaCO3). The total

hardness is calculated as a mathematical equation from the amount of calcium and

magnesium and is expressed in units of mg/L. Total alkalinity as CaCO3 expressed in mg/L is

the total amount of carbonates, bicarbonates, hydroxides, borates, phosphates, and silicates.

The analysis method is a titration with a hydrochloric acid solution to pH 3.7 end-point.

Total organic carbon (TOC) is the covalently bonded carbon in organic molecules and does

not represent any other organically bound elements. Higher levels of TOC are seen in waters

such as wastewater. TOC is a high temperature combustion technique and IR detection

method.

Methods used to analyse total metals include ion chromatography, inductively coupled

plasma atomic emission spectroscopy (ICP-AES), and atomic adsorption spectrophotometry

(AAS). During the collection of unfiltered water samples, each sample container contained

hydrochloric acid as a preservation method. The following total metials were analysed,

aluminum (Al), boron (B), calcium (Ca2+), iron (Fe), potassium (K+), magnesium (Mg2+), sodium

(Na+), strontium (Sr) and manganese (Mn).

Sulphate (SO42-) is determined titrimetrically with barium chloride solution using thorin as

the indicator. The sample is treated with a cation exchange resin prior to titration.

Silica (SiO2) can have negative impacts on water sources at increased levels and can cause

algal blooms. The analysis method for SiO2 is automated molybdite-reactive silica method

and the unit of measurement is mg/L.

The analysis of bromide (Br-) involved filtering samples through 0.45 μm pore size of a cellulose

acetate filter. The filtered sample is analysed using a spectrophotometric method and the unit

of measurement is in mg/L. Chloride (Cl-) analysis is undertaken using the Mohr titration method

or the mercurimetric titration method for samples with expected concentration of <10mg/L. The

concentration of fluoride (F-) is measured using a fluoride electrode and a pH meter to measure

the activity of fluoride ions in the water sample. This can be undertaken as fluoride activity is

proportional to pH.


© 2016 Page 40

QUALITY CONTROL

The National Association of Testing Authorities (NATA) is the authority that regulates

laboratory facilities in Australia and the laboratory chosen to undertake independent

sampling for this research project, ALS, is accredited by this association.

NATA is an independent accreditation which assured that technical competence was met to

a specific standard that was consistent with all laboratory facilities in Australia. This

accreditation related to testing, inspection, calibration, systems, products and any other

related activities undertaken by the laboratory. The laboratory was provided with

documentation of accreditation that is available on the ALS website.

Quality control at ALS was undertaken by use of laboratory duplicate, method blank,

laboratory control spike and matrix spike. The laboratory duplicate was a randomly selected

intra-laboratory split which identified method precision and sample heterogeneity [103]. The

permitted ranges for the relative percent deviation (RPD) ranged from 0-50 % depending on

the concentration above the limit of reading (LOR) for the analysis method used. The method

blank referred to an analyte free matrix to which all reagents were added in the same

volumes or proportions as used in standard sample preparation [103]. This method

monitored potential laboratory contamination. The laboratory control spike was a known

interference free matrix spiked with target analytes. This method monitored precision and

accuracy independent of the sample matrix [103]. Matrix spike was an intra-laboratory split

sample spiked with a representative set of target analytes. This method monitored potential

matrix effects on analyte recoveries. All methods were presented in reports from ALS with

the water sample analysis reports.

MODELLING

Graphs

Modelling of the results was initially undertaken using Microsoft Excel 2011, version 14.4.4

using the graphing tools. This was used to analyse, compare and draw conclusions regarding

the physical and chemical parameters for the CS water.

Principal Component Analysis

Principal component analysis (PCA) was used to determine relationships between water

quality parameters, CSG production fields and location within each and between fields.


© 2016 Page 41

Water quality analysis historically has been assessed using a comparison method with the

tested parameter being compared to a recommended value [104, 105]. Environmental data

has been successfully assessed using chemometric techniques in a number of situations

including wastewater monitoring, water classification, selecting water sources for human

consumption, and evaluation of pollution [106]. Chemometrics can provide useful

information about the origin of particular water quality parameters, the anthropogenic

activities, management techniques of the water, the complex interpretation of

hydrochemical data, and the exact parameters of most importance. PCA is a method of

chemometric analysis that has been used in water quality data research and this information

can then be used to assess and manage water resources [104, 106, 107]. PCA is a multivariate

process of reducing data points to provide the most meaningful points, which are called the

principal components [104]. The new data points are orthogonal (completely independent)

and uncorrelated to each other [104].

Data pre-treatment was undertaken prior to PCA being performed and involved treating the

missing values with the value for the limit of reading. This was undertaken so that all values

would have a positive value. Auto-scaling was then used as a pre-treatment prior to PCA

being performed and involved a combination of mean centering and standardisation. Mean

centering used a calculation of the mean of each parameter for the entire data set which was

then subtracted from each corresponding data point. This removed any difference in size or

importance of measurements in the data set. Standardisation required each variable to be

divided by the corresponding standard deviation. Standardisation was used to remove

weighting that was artificially imposed by units of the variables. The combination of the two

methods resulted in data with zero mean and unit variance (standard deviation of 1). Further

pre-treatment was then undertaken by performing natural log on each variable, due to

negative values as an outcome of auto-scaling, a value of 100 was added to each variable.

This method normalised the data because there was variation between the order of

magnitude and analytical parameters [104]. Microsoft Excel 2011, version 14.4.4 including

the statistical software XLSTAT 2013.1 was used for PCA including the data pre-treatment.

Linear Regression Modelling

The Pearson Correlation Coefficient was used for linear regression modelling as it is a

measure of two sets of data and determined how well the data was related to each other

using a linear dependence around a line of best fit. Statistical analysis was undertaken using

Microsoft Excel 2011 version 14.4.4 including the statistical software XLSTAT 2013.1. Specific


© 2016 Page 42

parameters investigated were those that are outlined by the Queensland legislation which

are required to be analysed prior to CS water being re-used beneficially. Some of these

parameters were unable to be tested at the water source, and instead needed to be analysed

in a laboratory environment. Therefore the time and cost associated with testing was at

times significant.

The large amount of water that is present when CSG is extracted and also the extensive area

in which the CSG industry spans, results in a considerable amount of water sampling and

testing being required. The use of surrogate indicators for water quality parameters that

must be tested in a laboratory is therefore beneficial.

Surrogate indicators were chosen for water quality parameters, TSS, TDS and SAR as they are

frequently required to be tested prior to CS water being used and they are most accurately

tested in a laboratory. The surrogate indicators were those that can be tested at the water

source and included turbidity and EC. The surrogate indicators were chosen based on the

correlations between parameters and the known relationships as shown in the literature [77,

108].

This study identified surrogate indicators for a specific set of water samples from 150 CSG

production wells in a small geographical location in the Surat Basin. The extrapolation of this

data has not been extended to areas outside of the study area. The surrogate indicator

equations were developed using Microsoft Excel 2011, version 14.4.4.

Scaling Potential Simulations

The CS water for this study was based upon samples collected from 3 different fields (A, B,

and C) in the Surat Basin, Queensland [Tables 8, 9 & 10] Due to confidentiality reasons we

cannot provide more specific information about the fields of interest. Average, minimum,

and maximum values were evaluated in order to determine the robustness of the predicted

reverse osmosis system performance. Overall, the CS water studied ranged from medium-

salinity brackish water (TDS <5000 mg/L) to high-salinity brackish water (TDS 5000 – 15000

mg/L) with medium to low Total Organic Carbon (TOC) [91]. The following tables show the

water quality for each field:


© 2016 Page 43

Table 8: Values for ROSA Model Field A

Parameter (mg/L) Average CS Water Minimum

CS Water

Maximum CS

Water

Ammonium 1.06 0.77 1.9

Potassium 6.91 4 14

Sodium 1487.02 909 2700

Magnesium 3.78 1 16

Calcium 9.04 2 55

Strontium 2.3 0.65 9.03

Barium 1.37 0.526 4.39

Carbonate 38.09 5.0 203

Bicarbonate 1038.59 276 1620

Nitrate <0.01 <0.01 <0.01

Chloride 1595.41 471 4390

Fluoride 2.17 0.8 3.2

Sulphate 1.57 <1 18

Silica 16.91 13.1 19.6

Boron 0.34 0.22 0.54

pH 8.47 7.92 8.89

Total Dissolved Solids 4443.52 2490 7600


© 2016 Page 44

Table 9: Values for ROSA Model Field B


CS Water

Maximum CS

Water

Ammonium 1.26 0.72 1.81

Potassium 6.08 3 10

Sodium 1451.86 786 2010

Magnesium 3.12 1 8

Calcium 6.96 3 19

Strontium 2.12 0.699 4.5

Barium 1.18 0.379 2.32

Carbonate 30.14 12 80

Bicarbonate 959.78 470 1540

Nitrate <0.01 <0.01 0.03

Chloride 1579.37 875 2930

Fluoride 2.01 1 3.3

Sulphate 1.96 1 48

Silica 17.73 13.9 23.1

Boron 0.41 0.24 0.68

pH 8.43 7.94 8.76

Total Dissolved Solids 4046.44 2190 5790

Reverse Osmosis System Analysis (ROSA) by Filmtec is a membrane system development

program. ROSA was used in this study to perform a simulation on the CS water to investigate

the potential for scaling. IMS Design by Hydranautics is a software design program that runs

a similar simulation to that of ROSA. This software was used in conjunction with ROSA to

simulate CS water from this study as it predicted not only the concentration of permeate but

also the scaling potential.


© 2016 Page 45

Table 10: Values for ROSA Field C


CS Water

Maximum CS

Water

Ammonium 1.31 0.84 2.7

Potassium 10.63 5 20

Sodium 2098.33 1130 3700

Magnesium 8.79 1 34

Calcium 26.17 3 137

Strontium 5.52 0.994 20.2

Barium 2.73 0.622 9.38

Carbonate 101.54 12 482

Bicarbonate 713.92 168 1350

Nitrate <0.01 <0.01 <0.01

Chloride 2938.04 823 5910

Fluoride 1.6 0.4 2.7

Sulphate 1.38 1 5

Silica 16.46 13.8 19.2

Boron 0.31 0.17 0.61

pH 8.3 7.83 8.63

Total Dissolved Solids 5655 3050 10200

The water type chosen for this simulation was CS well water with a silt density index (SDI) <3

which is a water quality that most resembled that of the CS water parameters when it is pre-

filtered. The SDI of brackish water has been shown to be over 5 [91, 109] and it is a measure

of the quantity of particulate matter in water which correlates with the fouling tendency of

RO and nanofiltration systems [91]. Therefore, the CS water would normally be pre-treated

with microfiltration (MF) or ultrafiltration (UF) prior to RO. This is common in the Australian

CSG industry with all CSG operating companies using some form of pre-treatment such as

microfiltration, ultrafiltration, disc filtration, ion exchange, flocculation, ballasted, and/or


© 2016 Page 46

micro-sand [47, 54, 80-83]. It has been shown that SDI can impact on permeate TDS, power

consumption, and cost [97].

The membrane selection is dependent on using either the ROSA or IMS Design simulation.

The membrane chosen for the ROSA simulation was BW30-2540 balanced with NaCl. The

membrane is a high rejection brackish water membrane with manufacturer specifications

that suited parameters of the CS water from this study [1, 2, 7, 14, 65]. The membrane

chosen for the IMS Design simulation was ESPA-2540 which is a brackish water high rejection

membrane also compatible with the CS water compositions studied [109]. The temperature

of the water was set at 25°C for the simulations with ROSA and IMS Design. The recovery

rate was set to 70% for the simulations with both ROSA and IMS Design, and it was shown

through simulation that if the recovery rate was reduced the Langlier Saturation Index (LSI)

would concomitantly reduce. However, for this study the lowest recovery rate that was

deemed satisfactory for field applications was 70%.

For brackish water with TDS <10,000mg/L, LSI expressed the potential for calcium carbonate

scaling [91]. The LSI was a positive value without pre-treatment and in order to control

calcium carbonate scaling the LSI must be adjusted to a negative value [91]. Adding acid to

the feed solution will decrease the LSI value and will also change the pH [91]. The simulation

was run with no pre-treatment, and if the LSI was > 0 hydrochloric acid was added to adjust

the pH and therefore reduce the LSI and subsequently the pH. Hydrochloric acid was chosen

for pH adjustment as the CS water in this study showed high barium content which may have

precipitated if sulphuric acid was used.

The system configuration that was used in this study was a 1 stage pass with 8 pressure

vessels in each stage and 6 elements in each vessel. This system was chosen in order to

simplify the simulation and mimic a plant that would treat 5000 m3 of feed water per day

with a recovery rate of 70 – 75%. More complex system configurations were not evaluated

in this study.

LIMITATIONS

The CSG production wells in this study were not correlated with the geological bore logs from

the well itself due to the analysis using univariate and multivariate analysis not identifying

any specific patterns which would require further analysis of the bore logs. The geological

discussion made within this study was that from the literature only.

Chapter 4: Results & Analysis – Water Quality

© 2016 Page 47

3Chapter 4: Results & Analysis – Water

Quality

The chemical composition of CS water although not well reported in Australia has been

described in other countries such as the US and New Zealand. The CS waters from CSG

extraction in New Zealand and the US generally have high bicarbonate 402-435 mg/L (HCO3),

high sodium 184-334 mg/L (Na+), low calcium 6-20 mg/L (Ca2+), low magnesium 0.9-6.5 mg/L

(Mg2+) and low sulfate 0.7-27.6 mg/L (SO42-) with high chloride 49.3-146 mg/L (Cl-)

concentrations [1, 5, 38, 42]. Other parameters that are characteristic of CS water are high

sodium adsorption ratio, high total dissolved solids and high alkalinity [1, 38, 44]. Factors

that have been reported as possibly having an effect on the chemical composition of CS water

include location of the gas fields and depth of the coal seam [7, 50]. The chemical

composition of untreated CS water normally renders it unsuitable for beneficial use therefore

it is necessary for a treatment method to be implemented.

Adequate evaluation of CS water quality data is therefore highly important. It has been

shown that large data sets can be generated for water quality monitoring in areas which are

highly regulated by legislation. However, through the use of chemometrics (a multivariate

analysis application) the data can be analysed more efficiently [110]. Historically, water

quality analysis has been assessed using a comparison method with the tested parameter

being compared to a recommended value [104, 105]. Environmental data has been

successfully assessed using chemometric techniques in a number of situations including

wastewater monitoring, water classification, selecting water sources for human

consumption, and evaluation of pollution [106]. Chemometrics can provide useful

information about the origin of particular water quality parameters, the anthropogenic

activities, the management techniques of the water, the interpretation of hydrochemical

data, the spatial and temporal variability, seasonal effect and can identify important

parameters that can be used to assess and manage water resources [104, 106, 107, 111, 112].

The CS water was analysed using both univariate and multivariate analysis. Parameters

chosen for analysis were significant due to levels being legislated by the Queensland

Government and controlled when the water was used by other industries or CSG operating


© 2016 Page 48

companies. All parameters have the potential to adversely impact the environment or the

industry that the CS water is being used for as beneficial re-use. Parameters for analysis were

also chosen on the basis of the impact to the environment, for example, the potential for

excessive levels of particular elements to cause damage to soil or plant toxicity. In addition,

parameters that can impact the efficiency and productivity of treatment technologies

commonly used in processing CS water prior to use, such as RO, have also been included in

the analysis. The water quality parameters included in this analysis were pH, SAR, CaCO3, B,

F-, SiO2, TOC, SO42-, Fe2+, Fe3+, Mn+, Al3+, EC, TDS, Hardness, Cl-, Br-, Sr+, Ca2+, Mg2+, Na+, and

K+.

CHEMICAL COMPOITION OF CS WATER

The chemical composition of CS water in this study had a high pH, bicarbonate alkalinity (as

CaCO3), Na+, Cl- and low Ca2+, Mg2+and SO42-. The descriptive statistics for the CS water

samples were undertaken to describe the mean, standard deviation, standard error,

minimum and maximum values of the dataset and therefore the range for each parameter

[1, 5, 10, 38, 42]. The similarity between chemical composition of New Zealand, US and

Australian CS water has been described in other studies and has been attributed to the

geochemical processes that act on the CS water, the depth of burial, the mixing of waters

from varied aquifers around the coal seam, recharge process and the coal rank [1, 5, 10, 38,

42]. The coals seams in Australia are the oldest; being deposited in the Jurassic to Cretaceous

(145.5 Ma), followed by the US from the upper Cretaceous (65.5 Ma) to the Paleocene (55.8

Ma) and New Zealand being the youngest deposited in the Eocene (55.8 – 33.9 Ma) [1, 5, 10,

38, 42].

DESCRIPTIVE STATISTICS

The descriptive statistics which were undertaken to describe the mean, minimum and

maximum values of the dataset and therefore the range for each parameter. This has been

described for each field separately and included the total 150 well sites. The descriptive

statistics were first undertaken to identify if there were any differences between each

production field being A, B or C. It was shown that there were differences between the three

Fields for the parameters minimum and maximum values shown in the following tables:


© 2016 Page 49

Table 11: Minimum and Maximum Values of Parameters Tested from Surat Basin CS water

Parameter

mg/L unless otherwise

specified

A Field B Field C Field

EC (mS/cm) 3850 – 13300 3630 – 9410 5150 – 17200

SAR (ratio) 69.6 – 177 86.4 – 163 62 – 156

pH (pH units) 7.92 – 8.89 7.94 – 8.76 7.83 – 8.63

TSS 5-7560 6-1520 7-265

TDS 2940 – 7600 2190 – 5790 3050 – 10200

Hardness 276 – 1620 12 – 80 12 – 482

CaCO3 5 – 203 470 – 1540 108 – 1350

Br- 1.93 – 12.7 2.82 – 11.7 2.75 – 16.6

Cl- 471 – 4390 875 – 2930 823 – 5910

SO42- 1 – 18 1 – 48 1 – 5

Ca2+ 2 – 55 3 – 19 3 – 137

Mg2+ 1 – 16 1 – 8 1 – 34

Na+ 909 – 2700 786 – 2010 1130 – 3700

K+ 4 – 14 3 – 10 5 – 20

Al3+ 0.02 – 40.9 0.01 – 17.8 0.01 – 2.08

Mn+ 0.002 – 0.54 0 – 3.59 0 – 0.13

Sr+ 0.65 – 9.03 0.7 – 4.5 0.99 – 20.2

B 0.22 – 0.54 0.24 – 0.68 0.17 – 0.61

Fe+ 0.16 – 45.1 0.09 – 351 0.3 – 6.16

SiO2 13.1 – 19.6 13.9 – 23.1 13.8 – 19.2

F- 0.8 – 3.2 1 – 3.3 0.4 – 2.7

Ba 0.53 – 4.39 0.38 – 2.32 0.62 – 9.38

Sr 0.65 – 9.03 0.7 – 4.5 0.99 – 20.20

TOC 1 - 71 1 - 138 4 – 138


© 2016 Page 50

Table 12: Average Parameter Values from Surat Basin CS water

Parameter

mg/L unless otherwise

specified

Field A Field B Field C

N 54 73 23

Mean

EC (mS/cm) 7084.26 6742.88 9764.58

SAR (ratio) 120.05 121.18 112.48

pH (pH units) 8.47 8.43 8.3

TSS 434.72 271.88 72.13

TDS 4443.52 4046.44 5655

Hardness 38.09 30.14 101.54

CaCO3 1038.59 959.78 713.92

Br- 6.03 5.57 8.87

Cl- 1595.41 1579.37 2938.04

SO42- 4.44 8.0 3.25

Ca2+ 9.04 6.96 26.17

Mg2+ 3.83 3.12 8.79

Na+ 1487.02 1451.86 2098.33

K+ 6.91 6.08 10.63

Al3+ 2.92 2.08 0.65

Mn+ 0.06 0.11 0.04

Sr+ 2.30 2.12 5.52

B 0.34 0.41 0.31

Fe+ 5.12 8.73 2.44

SiO2 16.91 17.73 16.46

F- 2.17 2.01 1.6

Ba 1.37 1.18 2.73

Sr 2.3 2.12 5.52

TOC 19.44 24.88 27.36

The descriptive statistics showed that further investigation should be undertaken for each

parameter separately and this was done using graphs to illustrate the concentration for each


© 2016 Page 51

production well in Fields A, B and C and to determine if they were similar and within a specific

range to comply with legislative guidelines.

SOLUTION PH

Figure 2 shows pH values from the sampled production wells for Field A, B and C with values

ranging from 7.83 to 8.89, with an average of 8.43. The current Queensland legislation for

discharge of CS water is dependent upon the environment or industry in which it is to be

used, however, it can be used in most applications with a pH of between 6 to 9 [48]. During

the degassing process, as the CS water was removed and brought to the surface, it can exhibit

a higher pH than exists when the CS water is within the coal seam aquifer [38]. This is because

the CS water is stabilised by the geological formation and therefore the pH can be shown to

be stable over time [4]. CS water has been demonstrated to be different between projects

with Taulis and Milke reporting a pH of 7.65 to be high in their study on CS water in

Maramarua, New Zealand [5]. McBeth et al., described a pH value of 8.26 to be high and

characteristic of CSG water in holding ponds in Wyoming, US [41]. This latter data, supported

the conclusion that pH is highly variable between CS water sources, with this study showing

a range of 1.6 pH units between all three Fields and within each Field.

ALAKALINITY

Previous research has shown that a high concentration of HCO3- is common for CS water

within locations such as the Surat Basin [10, 34], New Zealand [1, 5, 10, 38, 42], and the US

[1]. Current Queensland legislation stipulates a range of 20-100 mg/L for hardness (CaCO3)

to ensure that chemical tolerance levels are not exceeded for the aquaculture industry when

CS water is used in this application [48]. Criteria have also been outlined for CS water for

beneficial use for irrigation with a maximum bicarbonate ion concentration of 100 mg/L [48].

Bicarbonate alkalinity as CaCO3 from the CS water samples in this study showed high values

and a large range with a maximum across Fields A, B and C of 1620 mg/L and a minimum of

168 mg/L. As shown in Figure 2, the CS water from this study exceeded the Beneficial Use

Approval for all applications as outlined by the Queensland Government and would therefore

require treatment prior to use [48]. Chaffee et al. has found that the amount of ash yield can

indicate the presence of inorganics or minerals; the Surat Basin coals have indicated this

presence and can be described in terms of materials such as CaCO3 [113]. HCO3- found in CS

water has been reported as being high due to multiple processes, such as cation exchange

and methanation. The process of cation exchange and bicarbonate derived precipitation of


© 2016 Page 52

calcite (CaCO3) and dolomite (CaMg)(CO3)2 reduces SO42- and subsequently increases HCO3

-,

whilst depleting Ca2+ and Mg2+. These cation exchange reactions are suggested to be the

primary pathway for high levels of HCO3- in CS water [1, 38]. Another process that increases

HCO3- is the dissolution of carbonate (CO3

2-) by the methanation process, which involves the

decomposition of organic material [42]. The accumulation of HCO3- can occur when not all

of the CO2 is converted during the methanation process and is converted to HCO3-, which

then remains trapped in the CS water [42]. Lastly, the infiltration of HCO3- at the outcrop

(visual exposure of bedrock) through groundwater recharge (inflow of water to the

groundwater system from the surface) may also contribute to HCO3- concentrations in CS

water [1, 9, 26].

Figure 2: pH and Bicarbonate Alkalinity as CaCO3 of CS water for the A, B and C Field in the

Surat Basin

SODIUM IONS

High Na+ concentrations typically found in CS water can be detrimental to the environment

and should be reduced to a lower level prior to use in beneficial applications, such as

irrigation water [44]. The amount of Na+ in water may have an effect on the soils ability to

7.6

7.8

8.0

8.2

8.4

8.6

8.8

9.0

1 11 21 31 41 51 61 71

pH

Well Number


0

300

600

900

1200

1500

1800

1 11 21 31 41 51 61 71

CaC

O3

mg/

L

Well Number



© 2016 Page 53

be permeable and a high concentration of Na+ can result in a soils inability to hold water, and

also its ability to allow water to flow through the soil that causes lateral flow [114]. Na+ is

adsorbed into soils at the expense of Ca2+ and Mg2+ which are essential nutrients for plant

growth and development [3, 115]. Soils with high Na+ content have a tendency to be

dispersive erode more easily and also lose the ability to uptake water, increasing the

potential for runoff [32, 43].

Figure 3 shows a high content of Na+ in the CS water samples with an average of 1567 mg/L

and a range of 786 – 3700 mg/L. High Na+ content of CS water can be attributed to ion

exchange between minerals and water when the CS water is found within clays [38], which

is shown in geological bore logs from the production wells sampled [38]. A high Na+ content

has also been described for CS water in Queensland, New Zealand and the US [1, 38, 44].

Taulis and Milke (2012) and Wang et al. (2012) reported high Na+ concentrations at 300 and

563mg/L respectively. However these latter values were significantly lower than the Na+

content found in this study, in the Surat Basin [1, 38, 44].

CHLORIDE IONS

A study in the US from six producing basins (Powder River, Uinta, San Juan, Piceance, Raton,

and Black Warrior) has found that coals influenced by marine beds (the influence of the

marine environment when the deposits are being formed) have increased Cl- and Na+

contents with variations attributed to groundwater infiltration and the recharge zone [1].

Queensland legislation has also set a limit for Cl- for the beneficial use application for CS water

when used for livestock drinking water at 2000mg/L [48]. Figure 3 shows the high and

variable Cl- concentrations in the CS water sampled in this study with a range of 471 to 5910

mg/L. The highest values were shown in the C field with 67 % exceeding 2000 mg/L, whilst

Field A and B showed only 22 % and 11% exceeding 2000 mg/L respectively. This latter trend

was also apparent in the concentrations of Na+, with the highest values being described by

Field C. Cl- concentrations can also have an effect on plant growth, even though they are a

necessary micronutrient, as all elements essential for plant function can become toxic at

particular concentrations [116]. The current Environmental Authority and the Beneficial Use

Approval do not specify a concentration limit for Cl- for the use of CS water for irrigation

purposes [47, 48].


© 2016 Page 54

Figure 3: Na+ and Cl- Values of CS water for the A, B and C Field in the Surat Basin

HARDNESS

Hardness in groundwater is described by Ca2+, Mg2+ and HCO3-. High levels of these

parameters can result in the formation of insoluble CaCO3. Problems associated with CaCO3

include the build-up of this insoluble material on operating components of treatment

technologies such as the membranes of the RO plant, which requires continual maintenance.

Ca2+ and Mg2+ levels are regulated in the Australian Drinking Water Guidelines with a limit of

200mg/L permissible [117]. Research by Van Voast on CS water states that when HCO3-

values range from approximately 100 to 1000 mg/L, Ca2+ and Mg2+ values are below 50 mg/L

and decrease with increasing HCO3- [1]. Van Voast’s research was based on CS water across

six principal producing basins in the US [1]. The same trends for HCO3-, Ca2+ and Mg2+ were

shown in other studies from Australia and New Zealand [5, 10, 38, 42].

Figure 4 shows the variability of Ca2+ and Mg2+ concentrations from the sampled CS water.

The values on average were low, 11 mg/L for Ca2+ and 4.28mg/L for Mg2+. All values for Ca2+

were below 52 mg/L except for two locations in Field C with a concentration of 137 and 106

0

500

1000

1500

2000

2500

3000

3500

4000

1 11 21 31 41 51 61 71

Na+

mg/

L

Well Number


0

1000

2000

3000

4000

5000

6000

7000

1 11 21 31 41 51 61 71

Cl-

mg/

L

Well Number



© 2016 Page 55

mg/L. All values for Mg2+ were below 18 mg/L except for the two corresponding wells with

high Ca2+ values and were 33 and 34 mg/L, respectively. On average, Field C showed the

highest average for Ca2+ and Mg2+ and was approximately 2 – 3 times higher than that of

Fields A and B.

As shown in Figure 4 the two wells with higher concentrations of Ca2+ and Mg2+ were within

close proximity to each other (approximately 600 m). However, there were two wells that

were in closer proximity to both wells (approximately 100 – 300 m) that did not show high

values. The depth of the two wells showing high Ca2+ and Mg2+ were between 250 to 280 m

deep, while those closer in proximity were further down at 420 to 440 m deep. Well depths

in Field C ranged from 154 – 524 m. The variance in depth and thus the geological

composition was believed to be responsible for the large variance in Ca2+ and Mg2+ between

wells. The Walloon Coal Measures consist of the Macalister Coal Seam, Lower Juandah Coal

Measures, and Taroom Coal Measures, which are of the greatest depth. They are separated

by two sandstone formations which act as aquifers and are contained by the Upper Walloons

Formation and the Euromabah Formation which act as aquitards [26].

The low Ca2+ and Mg2+ concentrations shown in CS water were presumably due to inorganic

precipitation of calcite (CaCO3) and dolomite (CaMg)(CO3)2, which occurs when solubility is

reduced in the presence of HCO3- [1, 38]. The relationship between high bicarbonate and

reduced SO42-, also was an indication of low Ca2+and Mg2+concentrations in the CS water [1].

SO42- concentration in the CS water from this study was also low and possibly occurred due

to the SO42- reduction process during the decomposition of anaerobic bacteria, as they

consumed the organic matter [42].

BARIUM AND STRONTIUM IONS

Barium and strontium can be partially removed during water treatment such as desalination or

the process of dilution [118]. Water quality parameters such as Ba and Sr have been found to be

more susceptible to being transported in water, and studies such as Warner et al. showed that

shale gas water post treatment when released to surface waters contain concentrations of Ba

and Sr, although levels had been reduced from pre-treatment levels [118]. Figure 4 shows the Ba

and Sr concentrations for Fields A, B and C: Ba ranged from 0.38 – 9.38 mg/L, while Sr ranged

from 0.65 – 20.20 mg/L. Ba and Sr can cause scaling problems when concentrations are present

in the treated water and re-use methods can become limited [118]. An example is the use of


© 2016 Page 56

treated CS water for hydraulic fracturing in which the water containing Ba and Sr can cause

damage to metal equipment [55].

Figure 4: Ca2+ and Mg2+ Values of CS water for the A, B and C Field in the Surat Basin

0

20

40

60

80

100

120

140

160

1 11 21 31 41 51 61 71

Ca2

+m

g/L

Well Number


0

5

10

15

20

25

30

35

40

1 11 21 31 41 51 61 71

Mg2

+m

g/L

Well Number



© 2016 Page 57

Figure 5: Ba and Sr Values of CS water for the A, B and C Field in the Surat Basin

ALUMINIUM AND IRON IONS

Figure 5 shows the Al and Fe concentrations for the A, B and C Field for the CS water samples.

The Al concentration ranged from 0.01 to 40.9 mg/L and the Fe concentration from 0.09 to 45.1

mg/L. There was generally a direct relationship between the recorded Al and Fe concentrations

in each well. CSG water quality from the US has shown that Al3+ concentrations can vary when

samples are taken from either production wells or from discharge ponds [119]. Dissolved iron is

one parameter that can restrict CS water from being treated by RO if it is found at high

concentration [46]. A study in the US has shown that Fe3+ in CS water can commonly exceed

drinking water guidelines, and guidelines for uses such as irrigation or livestock drinking water

[18]. Similarly studies from groundwater in CSG exploration wells in Canada have shown that

levels of Fe3+ exceed the limitations in which aquatic life can be sustained [46]. This is in contrast

to Fe3+ concentrations in CS water from Maramarua, New Zealand where only trace elements

were present [5]. In the Surat Basin the concentration of Al3+ and Fe3+ is shown to be relatively

high as it exceeds the Australian drinking water guideline limits of 1.159 and 1.324 mg/L,

respectively. Iron concentrations in Bowen Basin CSG production wells have shown a range of

0

2

4

6

8

10

1 11 21 31 41 51 61 71

Ba

mg/

L

Well Number


0

5

10

15

20

25

1 11 21 31 41 51 61 71

Sr m

g/L

Well Number



© 2016 Page 58

0.57 to 16.6 mg/L [3]. The average concentration levels of dissolved iron in fields A, B and C were

5.12, 8.73 and 2.44 mg/L respectively.

Figure 6: Al and Fe Values of CS water for the A, B and C Field in the Surat Basin

TOTAL DISSOLVED SOILDS AND ELECTRICAL CONDUCTIVITY

The salt content (NaCl) of CS water impacts the TDS and EC content, and it has been shown

in previous studies that the CS water in Queensland has relatively high salt concentrations

[3, 44]. CS water from New Zealand has high and low salt contents, which was attributed to

the location of the well within the basin and its distance from the area of recharge that dilutes

the salt concentration, as recharge water mixes with CS water [42]. This study has shown a

large range for both TDS and EC. Knowledge of salt content is important for irrigation

applications as an increased level in soil can be detrimental to plant growth and development

[115].

The TDS and EC content of the CS water, as shown in Figure 7, were comparatively high with

an average of 4444 and 7345 mS/cm, respectively. There was a wide range for both the TDS

and EC contents for the CS water with the TDS value ranging from 2190 to 10,200 mg/L and

EC ranging from 3630 to 17,200 mg/L. Salt content has been regulated by the Queensland

Government through the Environmental Authority in which the limit for TDS is 1500 mg/L for

use in the applications of construction water (compaction) and dust suppression water, while

the Beneficial Use Approval states the TDS limit to be 300 to 6000 mg/L for livestock drinking

0

10

20

30

40

50

1 11 21 31 41 51 61 71

Al m

g/L

Well Number


0

10

20

30

40

50

1 11 21 31 41 51 61 71

Fe m

g/L

Well Number



© 2016 Page 59

water and 3000 mg/L for irrigation [47, 48]. The salt content of CS water reported in this

study inhibited the use of the CS water for beneficial use apart from drinking water for some

species of livestock and would require treatment to produce a suitable water quality for

other applications [48].

Figure 7: TDS and EC Values of CS water for the A, B and C Field in the Surat Basin

SODIUM ADSORPTION RATIO

SAR is used to determine the ratio between Na+, Ca2+ and Mg2+ [44]. SAR predicts the effect

on a soils ability to form aggregates by breaking bonds in the chemical structure of the soil,

which increases erosion due to the small particle size [43, 114]. This effect is due to Na+ being

adsorbed in soil at the expense of Ca2+ and Mg2+ [44]. Salinity in soil can change ecosystems

by adaptation to more salt tolerant vegetation, which can have a significant impact on areas

in which agriculture, forestry or remnant vegetation are dominant [120]. Salinity in soils has

become a major problem in Australia and increased salinity has occurred from vegetation

clearance, irrigation, and land use such as drainage practices [120]. Figure 8 shows the SAR

0

2000

4000

6000

8000

10000

12000

1 11 21 31 41 51 61 71

TDS

mg/

L

Well Number


0

4000

8000

12000

16000

20000

1 11 21 31 41 51 61 71

EC μ

S/cm

Well Number



© 2016 Page 60

value in the CS water. It was found to be high with a range of 62 to 177 and an average of

119. Current legislated values for re-use of CS water in Queensland has a maximum range of

6 to 12. Based on the water quality of the wells in this study the untreated CS water could

not be used for irrigation purposes without further treatment.

Figure 8: SAR Values of CS water for the A, B and C Field in the Surat Basin

TOTAL SUSPENDED SOLIDS

TSS in CS water is regulated by the Queensland Government through the Environmental

Authority and the Beneficial Use Approval and has varying limits depending on the intended

application. Figure 9 shows that an average of 300 mg/L was found in Fields A, B and C. One

high value of 7560 mg/L was identified in a well in Field A, while another six wells had TSS

values of >1000 mg/L. Current beneficial use of CS water for aquaculture and human

consumption is limited by a TSS value of <40 mg/L, while the discharge of CS water to

waterways requires a TSS value of <180 mg/L [47, 48]. In its current form the CS water

analysed in this study does not meet these requirements and would require treatment.

TSS particulate matter size is important when RO treatment is being used for CS water

processing, and is normally removed prior to the RO membrane by use of screens, cartridge

filters, coagulation or flocculation [62]. It has been identified during the sampling program

that some water samples contained large amounts of visible coal fines and/or visible subsoil

or bedrock particles whereas other samples looked visibly transparent, which could account

for the variable TSS content.

0

50

100

150

200

1 11 21 31 41 51 61 71

SAR

mg/

L

Well Number



© 2016 Page 61

Figure 9: TSS Values of CS water for the A, B and C Field in the Surat Basin

FLUORIDE AND BROMIDE IONS

The Queensland Government has legislated F- in the Beneficial Use Approval for re-use of CS

water for industry and also in the Environmental Authority that governs discharging water to

the natural environment such as waterways. The inclusion of F- into the legislation is due to

the effect of F- on human health and has been reported to cause dental and skeletal fluorosis

in excessive amounts [121]. World Health Organization (WHO) limits for F- in drinking water

is set at 1.5 mg/L [122]. Br- has been found to have very low toxicity effects to humans and

as such does not have a specific concentration limit set by the WHO for drinking water,

however it has been suggested that the acceptable daily intake of Br- is 0.4 mg/kg of body

weight in humans [123]. Although the content of F- in CS water was low [Figure 10] with a

range between 0.4 and 3.3 mg/L and an average of 2 mg/L, the CS water is still deemed

unacceptable for cattle feedlot drinking water in Queensland (2 mg/L) and beneficial use for

irrigation (1 mg/L). Figure 10 shows that values for F- were above the 2 mg/L re-use limits for

cattle feedlot drinking water by 63 % for Field A, 45 % for Field B and 23 % for Field C. Figure

10 also shows that the Br- at the levels recorded for re-use or discharge, however there can

be implications for efficiency and maintenance of the RO membranes. There exist several

treatment methods that can be used to remove F- and Br- in CS water prior to RO and these

include chemical adsorption or precipitation, ion exchange, or by selection of appropriate RO

membranes [121, 124].

0

2000

4000

6000

8000

1 11 21 31 41 51 61 71

TSS

mg/

L

Well Number



© 2016 Page 62

Figure 10: Br- and F- Values of CS water for the A, B and C Field in the Surat Basin

BORON

Figure 11 shows that boron (B) was present in all CS water samples with an upper limit of

0.68mg/L. Different limits for B have been set for different applications of water with the

WHO setting the current limit for drinking water at 2.4 mg/L [125], thus the CS water was

compliant with regulations in all instances.

The removal of B in a typical desalination process has been shown to be difficult depending

on the treatment technology used [126-128]. RO operation has shown that the optimal

removal of B is dependent on pH, amount of passes of the water through the RO membrane

and the type of commercial membrane used. Even though RO is able to remove B, a

significant amount of energy is required to undertake this process [126]. Pre-treatment

methods for the removal of B prior to CS water being treated by RO may include adsorption

or ion exchange. Adsorption as a treatment technology is limited by pH, temperature, and

the properties of adsorbent used, however it is cost effective and can remove B to a low

0

0.5

1

1.5

2

2.5

3

3.5

1 11 21 31 41 51 61 71

F-m

g/L

Well Number


02468

1012141618

1 11 21 31 41 51 61 71

Br-

mg/

L

Well Number



© 2016 Page 63

concentration (<0.05 mg/L) [128]. RO membranes and ion exchange together have also been

found to be beneficial for B removal to reduce the cost associated with RO membranes alone

[126].

Boron present in CS water could be due to B being lost or released during the early stages of

the coalification process and is either organically combined or adsorbed to coal macerals or

inorganic matter [127]. Although B is required for all plant growth, at high levels B is toxic to

plants and animals (1 to 2 m/L) [128].

SILICA

Figure 11 shows the dissolved Si content in Fields A, B and C and is represented by a range of

13 – 23 mg/L. In Australia natural water has a range for Si of 1 – 30 mg/L and groundwater

generally has a range of 20 – 100 mg/L [129]. Si is one of the most complicated particles in

water purification and it can be found in soluble, colloidal, and suspended form [92]. The

solubility of Si can be a major limitation to the RO treatment as it can result in scaling

problems and can decrease the water production rates, as well as decrease energy efficiency

[92, 129, 130]. If insoluble Si is present in CS water it can impact on the RO treatment by

forming a layer on the surface of the RO membranes during the high pressure movement of

water across them [129].

PARAMETERS EXCLUDED FROM ANALYSIS OF CS WATER

The remaining parameters described in Chapter 3 that were below the detection limit for the

instrumentation used during analysis, and other parameters that have a low concentration

range are provided in the following table. The results of this study has shown that CS water

at these production wells do not have the potential to contain high concentrations of these

parameters and may be excluded from testing requirements in the future as legislated by the

Queensland Government. It should be noted that trace elements of parameters described

in Table 9, will increase and decrease in concentration when left for extended periods of time

in holding ponds [7]. A study in the US has shown increases in As in holding ponds, while

other studies show both increases and decreases from holding ponds over time for elements

such as aluminium, iron, arsenic, selenium, fluoride, barium, manganese, chromium and zinc

[39].


© 2016 Page 64

Figure 11: B and Si Values of CS water for the A, B and C Field in the Surat Basin

Table 13: Parameters Excluded from Analysis for CS water in the Surat Basin

Parameter Range (mg/L)

Residual Alkali 1.7 - 33

Total Metals

Ar Be Cd Cr Co Cu Pb Mo Ni Se V Zn

Highest average

0.03

Mercury <0.001

Trivalent Chromium <0.01 – 0.02

Hexavalent Chromium <0.01

Total Ammonia as N 0.72 – 2.7

Total Nitrogen 0.5 – 6.1

Total Phosphorus 0.01 - 1.48

Dissolved Organic Carbon 1 – 55

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

1 11 21 31 41 51 61 71

B m

g/L

Well Number


10

12

14

16

18

20

22

24

1 11 21 31 41 51 61 71

Si m

g/L

Well Number


Chapter 5: Results & Analysis – Principal Component Analysis

© 2016 Page 65

4Chapter 5: Results & Analysis – Principal

Component Analysis

PCA was performed on the water quality parameters and included all well sites that were

sampled during this study. This was undertaken to identify if Field A, B and C could be

geographically identified by water chemistry by either location or depth. Depth was

differentiated using CS water from the Juandah coal seam and the Taroom coal seam.

The biplot for the A, B and C Field for all water quality parameters is shown in Figure 12.

Three groups of water quality parameters described the data on both PC1 and PC2. Iron,

manganese, and aluminium were found to describe PC2. Bromide, magnesium, strontium,

potassium, hardness, calcium, chloride, EC, TDS and sodium appeared as a group and are

negative on PC1. A third group consisting of fluoride, bicarbonate alkalinity as CaCO3, SAR,

pH, boron, SiO2, TOC, and sulphate are positive on PC1. Sulphate and TOC were less

associated with the PC1 than the other parameters. It was found that PC1 and PC2 were

responsible for describing 67.8 % of the data.

There was no distinction between well sites from each field when the PCA was performed on

the entire data set, instead they were spread amongst each of the three groups of water

quality parameters. This data showed that water composition was not geographically

distinguished by the location of CSG production wells within the scale of this study.

Well sites from the Juandah coal seam consisted of 116 of 150 well sites sampled during this

study. Figure 13 shows that PC1 and PC2 were responsible for 67.4 % of the variance in the data.

Three similar groups are shown which describe PC1 and PC2 as shown in previous PCA performed

such as iron, manganese and aluminium which were identified to positively correlate for PC2.

Bromide, magnesium, calcium, chloride, hardness, EC, TDS, sodium, potassium and strontium

were highly correlated on the negative PC1 and fluoride, bicarbonate alkalinity as CaCO3, SAR,

pH, boron SiO2, TOC, and sulphate being positively correlated with PC1: sulphate and TOC being

only slightly correlated with this group as compared with other water quality parameters.


© 2016 Page 66

Figure 12: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field in the Surat basin

AAAA

AA

AA

AA

AA

A A

AA

A A

A

A

A

A

A

A

A

A

A

A

A

A

AA

AAA

AAA

A

A

A

A

AA

A

A

A

AA

A

A

A

A

A

B

B

BBB

B

B

BB

B

B

B

BB

B

BB

B

BB

B

B

B

B

B

B

BB

B B

B

BB

B

BBB

BBB

B

B

B

BB

B

BBBB

BBB B

B

BBB

BB

BB

B

B

BB

B

B

B

BB

BC

CC C

C

CC CC

CC

C

CC

CCC C CC

C

CC

pH

SAR

ECTDSHardness

Br-

Bicarb CaCO3

SO4-Cl

CaMgNaK

Al

Mn

Sr

B

Fe

SiO2

F-

TOC-18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 4 6 8

PC

2 (

11.3

%)

PC1 (56.5%)


© 2016 Page 67

Figure 13: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field for the Juandah Coal Seam in the

Surat Basin

AA A AA A

A AA A AAA

A AAA

AAAAA

AA A

A

A

AAA

AA

AA

A

BB

BB BB

B

B

BB B

B

B

B B

BB

B

B

B BB B

B

BBB

B BB

B

BB B B

BBBB BBB BB

B BBB B

BBB

BB B

B

B

BBB

B

CCC

CC CC

CC

CC CC C CC

CC C

pH

SARECTDSHardness

Br-

Bicarb CaCO3

SO4-ClCaMgNaK

Al

Mn

Sr

B

Fe

SiO2

F-TOC

PC

2 (

11.4

%)

PC1 (56.0%)


© 2016 Page 68

Well sites from the Taroom coal seam from this study consisted of 34 of 150 well sites

sampled and are shown in Figure 14. PC1 and PC2 described 62.7 % of the variance of the

data. Similar correlations were identified in the Juandah PCA with bromide, magnesium,

calcium, chloride, hardness, EC, TDS, sodium, potassium and strontium being highly

correlated on the negative PC1 and iron, manganese and aluminium grouped for PC2: but

negatively as compared with positively as shown for the Juandah PCA. A difference with the

parameters fluoride, bicarbonate alkalinity as CaCO3, SAR, pH, boron, siilca, which were

positively correlated on PC1 as seen in all other PCA that was performed, is that TOC and

sulphate are now correlated on negative PC1.


© 2016 Page 69

Figure 14: Biplot for the Two Principal Components from the PCA of Water Quality Parameters and the A, B and C Field for the Taroom Coal Seam in the

Surat Basin

A

A

AA

A

A AA

AAA

AA

A

A

AA

A

BB

B

B

B

B

B

BB

B

BBC

C

CpH

SARECTDS

HardnessBr-Bicarb CaCO3

SO4-Cl

CaMg

Na

K

Al Mn

Sr

B

Fe

SiO2F-

TOC

PC

2 (

17.5

%)

PC1 (45.2%)


© 2016 Page 70

PCA has identified 3 groups of correlated water quality parameters, which consist of:

1. EC, TDS, Hardness, Cl-, Br-, Sr, Ca2+, Mg2+, Na+, K+

2. Fe, Mn+, Al3+

3. pH, SAR, CaCO3, B, F-, SiO2 ,TOC, SO42-

As described PCA has found a strong correlation between parameters EC, TDS, hardness,

calcium, magnesium, sodium, chloride, potassium, bromide and strontium for PC1 for all PCA

performed. The strong correlation of these water quality parameters was consistent with

the known chemical relationships and the chemical composition that has been shown in

other studies of CS water such as high bicarbonate, high sodium, low calcium, low magnesium

and very low sulfate concentrations [1, 5, 38, 42].

The properties of clay minerals may contribute to iron, manganese and aluminium being

associated in a group for all of the PCA that were performed showing very strong correlations

between these elements. Considering that the Surat Basin coals show a high concentration

of clay over other common minerals and they can easily be stripped and dissolved into the

associated aquifers, it is believed that clays are responsible for the iron, manganese and

aluminium group in the PCA [28]. Chemical composition data described for coal has shown

that the common minerals are clay, carbonates, sulfide ores, oxide ores, quartz and

phosphates [28, 31]. However, mineral matter in coals can differ greatly even on a regional

scale, and it has been shown that the Surat Basin Jurassic coals are characterised by clay; with

pyrite, quartz and siderite (carbonate) found to be of low concentration [28, 31]. It has been

shown in the Surat Basin coals that this is common for the dominant clay minerals such as

illite, kaolinite, and montmorillonite [28, 31]. Chaffee et al. described the structural

characterisation of high volatile bituminous coals from the Walloon Coal Measures as being

dominated by kaolinite [Al2Si2O5(OH4)], which is a clay mineral [113]. Kaolinite is a Kaolin-

serpentine series clay mineral in which the Mg2+ in serpentine [Mg3Si2O5(OH)] can be

substituted with Fe3+ [131]. Salehy has also identified that common minerals of the Jurassic

coals from the Eastern Surat Basin are clay minerals [31].

Sulphate and TOC were two parameters that were not as closely correlated to the other

parameters of group 3 which included pH, SAR, CaCO3, boron, fluoride and silica. Sulphate

has been used to describe the chemical composition of CS water by a number of different

studies, however it has been shown to have a low content in Surat Basin coals and this could


© 2016 Page 71

contribute to the low correlation to both PC1 and PC2 during this study for fields A, B and C

[1, 5, 38, 42, 44]. The low sulfate content of the Surat Basin coals could be a result of the lack

of sulfide minerals such as pyrite [28, 31]. Closely associated were the parameters pH, SAR,

CaCO3, boron, fluoride and silica. The association of pH, SAR and CaCO3 although not

predicted have all shown an inverse relationship with EC and this could be the reason for

these parameters being shown as being not related to the group containing EC in the PCA.

The 3 groups described by PCA on the Surat Basin CS water can potentially be described by

the mineral content from the associated coal seams, however further multivatiate analysis

should be conducted in future work, particularly if comparisons between much larger data

sets are obtained from other locations across the Surat Basin. Although the CS water can be

explained partially by the mineral content, the PCA did not show any groups by geographical

location or depth of the well sites.

Chapter 6: Results & Analysis – Surrogate Indicators

© 2016 Page 72

5Chapter 6: Results & Analysis – Surrogate

Indicators

In this study we have investigated two significant parameters, namely SAR and TDS for prediction

using a surrogate indicator. EC of the CS water can be easily tested at the well head or

management dam, and is shown to be sufficiently accurate to be practically useful for assessing

water quality. This investigation concerned the analysis of the 150 water samples for the CSG

production wells in the Surat Basin.

The literature shows that there is a strong relationship identified between EC and both SAR and

TDS [77, 78, 132-134]. EC is a measure of salinity and is specifically related to the ability of water

to pass an electrical current [77]. The magnitude of the water electrical conductivity is affected

by ions that carry a negative or positive charge, mainly inorganic species [77]. Other factors that

can impact the EC value include the solution temperature (higher temperatures result in a higher

EC value) and the geology surrounding the aquifer from which the water is sourced [77, 78]. TDS

relates to EC as it is also a measure of salinity, more specifically the inorganic and organic

compounds in water (we note the precise correlation is site specific) [132]. TDS is calculated by

evaporating a solution until only dry matter remains. Since water has little to no electrical charge

the relationship between EC and TDS is normally positively correlated [132]. SAR is a measure of

the equivalents of exchangeable Na+, Ca2+ and Mg2+ ions in solution. A high SAR value and low

solution electrical conductivity may result in a greater detrimental effect on soils [135].

Water quality parameters tested in this investigation included EC, SAR and TDS. There was found

to be a negative correlation shown between EC and SAR (r=[-0.583] P=<0.005). Figure 15 shows

the relationship between measured and calculated SAR values for CS water.


© 2016 Page 73

Figure 15: Measured SAR vs. Calculated SAR as a function of well analyzed

The model used to calculate the SAR in CS water has shown that only 20 of the 150 water

samples were either 20 % greater or less than the actual value that was measured, this being

13 % of all the data. Only 7 of the 150 water samples were either 30 % greater or less, this

being 4.6 % of all the data.

As mentioned by Walton, EC values (μS/cm) are normally multiplied by 0.7 to estimate TDS

content (mg/L), which equates to a ratio of EC/TDS of 1.43 [118]. Calculation of the EC/TDS

ratio for the coal seam gas water samples from this study indicate that the average ratio was

1.66 (Figure 16). However, it was evident that there was considerable scatter in the data,

which is consistent with studies by Ali et al. who found that depending on water composition

the EC/TDS ratio for reclaimed industrial water ranged from 1.49 to 1.72 [134].

Statistical analysis showed a positive correlation between EC and TDS< (r=0.812, P=<0.005).

Figure 17 illustrates the relationship between measured and calculated TDS. The predictive

model used to calculate the TDS in CS water has shown only 6 of the 150 water samples were

either 20 % greater or less than the actual value that was measure, this being 4 % of all the

data.

60

80

100

120

140

160

180

1 26 51 76 101 126

Sod

ium

Ad

sorp

tio

n R

atio

(SA

R)

Well Number

Measured SAR Calculated SAR


© 2016 Page 74

Figure 16: Relationship between EC and Measured TDS as a function of well analyzed

Figure 17: Measured TDS vs. Calculated TDS as a function of well analyzed

The predictive models for EC-SAR and EC-TDS have been determined to be:

SAR = 157.944 + (-0.005) EC (μS/cm)

TDS (mg/L) = 416.60 + 0.548 EC (μS/cm)

Previous work in the area of surrogate indicators for water quality parameters such as these

is limited. For example, Settle et al. developed a predictive model for TDS using the surrogate

indicator EC in urban storm water [108]. In relation to correlating EC and SAR, Seilsepour and

1.2

1.4

1.6

1.8

2.0

2.2

1 26 51 76 101 126

Rat

io E

C/T

DS

Well Number

Measured Data Average Value

2000

4000

6000

8000

10000

1 26 51 76 101 126

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Well Number

Measured TDS Calculated TDS


© 2016 Page 75

Rashidi used linear regression models to predict soil SAR from EC [77, 78]. It has been

identified that two parameters were responsible for the prediction of soil salinity, that being

EC and SAR [78]. Soil salinity in Australia is of great significance due to its impact on plant

root growth and soil structure [53]. Soil salinity and sodicity affects plants by inhibiting water

uptake at the root zone and by toxicity or metabolic disruption by Na or Cl ions [53].

Seilsepour and Rashidi found that the soil SAR predicted by the linear regression model was

not significantly different from the SAR that was tested and recorded in the laboratory [78].

The research also suggested that dominant clay minerals, soil chemistry and pH can impact

on the relationship between EC and SAR and therefore the linear regression model should be

directly determined by the soil of interest [53, 78]. It is suggested that this may be due to

the high SAR concentration being associated with the increase in sodium at the expense of

calcium and magnesium due to cation exchange complex of clay particles [53]. Settle et al.

outlined that some water quality parameters such as TDS can be either specific to the water

catchment area due to the similarity of geological origin and form or generic across multiple

catchments [108].

The linear regression and predictive model for evaluating SAR and TDS from calculated EC

has been applied to data presented in various studies conducted in the US and Australia.

Studies assessed include: a study conducted on a CSG exploration well over 30 individual

sampling occasions, in Maramarua, New Zealand; a study conducted in the Bowen Basin,

Australia on the upper and lower seam north and south of a fault using mean values for CSG

production wells [3, 19, 38, 41, 43]. This analysis was undertaken to identify the practical

implications of a specific predictive model related to data from varied location.

CS water analysed in this study from different locations was variable in composition in terms

of EC, SAR and TDS. For example, the Australian and New Zealand CS water SAR value was

higher (approximately >100 to 200) than that of the US water (approximately 10 to 50). In

addition, the EC values for New Zealand water were 1,000 μS/cm, whereas in Australia the

CS water was up to 10, 000 μS/cm and in contrast the US water was considerably higher as

shown by conductivities up >100,000 μS/cm [3, 19, 38, 41, 43].

A linear regression using the Pearson Correlation Coefficient was performed on the data from

New Zealand, the US and the Bowen Basin in Australia. Data from Taulis and Milke (2012)

showed the New Zealand data neither exhibited a strong correlation between EC and TDS

(r=0.478 P=0.007) nor shows a correlation between EC and SAR (r=1.00 P=<0.572) [38].


© 2016 Page 76

Results from McBeth and Reddy (2003) showed a strong positive correlation between EC and

TDS (r=1.00 P=<0.0005) and EC and SAR (r=0.648 P=<0.0005). Figure 18 shows the

relationship between the calculated TDS and the measured TDS using the predictive model

for EC-TDS which has been determined as:

TDS (mg/L) = 0.323 + 639.722 EC (dS/cm)

Figure 19 shows the relationship between the calculated SAR and the measured SAR using

the predictive model for EC-SAR which has been determined as:

SAR = 5.714 + 3.872 EC (dS/cm)

Figure 18: Measured TDS vs. Calculated TDS Wyoming USA [41] as a function of well

analyzed

0

500

1000

1500

2000

1 6 11 16 21 26

Tota

l Dis

solv

ed S

olid

s (m

g/L)

Well Number

Measured TDS Calculated TDS


© 2016 Page 77

Figure 19: Measured SAR vs. Calculated SAR Wyoming USA [41] as a function of well

analyzed

A study by Rice (2003) analysed data from a coal bed methane field in Utah at 28 individual

well sites which were sampled on three occasions between June 1996 and March 1999 [19].

A linear regression was performed on the EC and TDS data from this study and it showed a

positive correlation (r=0.994 P=0.00). Figure 20 shows the relationship between the

calculated TDS and the measured TDS using the predictive model for EC-TDS, which was

determined as:

TDS (mg/L) = 0.382 + 770.701 EC (mS/cm)

The water from this study was derived from the Ferron Sandstone Member of the Mancos

Shale [19]. Dominant formations included sedimentary deposits in the delta from the

Cretaceous Period [19]. Kinnon et al. presented data from the Bowen Basin in Australia which

was taken from 24 CSG production wells from: the upper seam at approximately 200 – 300

m depth; and the lower seam at approximately 250 – 400 m depth [3]. The data used for this

communication included 4 mean values, 2 for the upper seam and 2 for the lower seam.

Figure 21 shows the relationship between the calculated TDS and the measured TDS using

the predictive model for EC-TDS which was determined as:

TDS (mg/L) = 1046.54 + 0.439 EC (dS/cm)

0

5

10

15

20

25

1 6 11 16 21 26

Sod

ium

Ad

sorp

tio

n R

atio

Well Number

Calculated SAR Measured SAR


© 2016 Page 78

Figure 20: Measured TDS vs. Calculated TDS Utah USA [13] as a function of well analyzed

Figure 21: Measured TDS vs. Calculated TDS Bowen Basin Australia [3] as a function of well

analyzed

The results presented in this study are of significance for the global CSG industry and in

particular for Queensland, as water quality parameters such as SAR and TDS are required to

be reported prior to use or disposal of CS water. However, these latter parameters are

normally determined by laboratory testing. The large and relatively remote geographical

area in which the Surat Basin CSG industry operates, can make the time between water

quality sampling and receiving laboratory tests lengthy. As a consequence, this delay may

0

10000

20000

30000

40000

50000

1 11 21 31 41

Tota

l Dis

solv

ed S

olid

s (

mg/

L)

Well Number

Calculated TDS Measured TDS

4000

4500

5000

5500

6000

6500

1 2 3 4

Tota

l Dis

solv

ed S

olid

s (

mg/

L)

Well Number

Calculated TDS Measured TDS


© 2016 Page 79

result in ineffective management of CS water. The application of a linear regression model

to form a predictive equation should be developed based on site water quality monitoring

data to ensure that any regional variations are taken into consideration [78, 108].

The early identification of the water quality parameters through the use of a predictive tool,

such as that described in this study may be helpful in the identification of the potential use

or disposal methods prior to the laboratory test results being available. This outcome can

result in reduced financial cost and prediction of the most effective treatment method and

use for specific CS water.

Chapter 7: Results & Analysis – Scaling Potential & Reverse Osmosis Design

© 2016 Page 80

6Chapter 7: Results & Analysis – Scaling

Potential & Reverse Osmosis Design

SCALING POTENTIAL

The scaling potential in ROSA and IMS Design can be determined in relation to barium

sulphate, calcium sulphate, strontium sulphate, calcium fluoride, silica dioxide, and

magnesium hydroxide as a percentage saturation, with greater than 100 % saturation

suggesting that there is a scaling potential for the RO membranes.

The CS water was initially simulated using ROSA and scaling potentials are displayed in

Figures 22 to 24. For all fields examined at all water compositions evaluated there was no

evidence to suggest that calcium sulphate or magnesium hydroxide exhibited any scaling

potential. Strontium sulphate had zero potential for scaling for all three fields for the average

and minimum CS water compositions, but did have a very small percentage (< 5 %) scaling

potential for the maximum CS water compositions in fields A and B. In contrast, barium

sulphate, calcium fluoride and silica were all predicted to present a higher risk of scaling

behaviour. In terms of barium sulphate, the minimum CS water composition was

characterized by a relatively moderate scaling potential for all three fields (<15 %). However,

the maximum CS water composition was more problematic for all three fields with high

scaling potentials predicted (100 % for Fields A, B & C). With the average CS water

composition the scaling potential was also moderate for all three fields (26, 29, 31 %

respectively). This result shows that the higher concentration levels in the feed water do

have an impact on the potential for scaling for RO membranes. The concentration of barium

in the feed water was highest in the C field (0.622 – 9.38 mg/L) whereas the A and B field

maximum values were 4.39 and 2.32 mg/L respectively. Barium sulphate has been shown to

be the most insoluble of all alkaline earth sulphates [91]. In brackish water the critical feed

concentration level of barium can be as low as <5 μg/L [91].

Calcium fluoride was identified as a possible major problem in relation to reverse osmosis

treatment of the CS water. The scaling potentials were universally estimated to be high

enough to result in scale formation (75, 28 and 100 % for Fields A, B & C, respectively) for the

maximum CS water composition. However, for the average and minimum CS water

compositions the scaling potential was drastically reduced to significantly safer levels (<10


© 2016 Page 81

%). These results were consistent with the results for the scaling potential for barium

sulphate for Fields A, B and C. If the calcium concentration is high in the feed water then

fluoride can cause scaling at concentration levels of 0.1 mg/L or higher [91]. The

concentration of fluoride in the feed water from this study was highest in the B field (3.3

mg/L) however all fields showed a relatively similar range. The calcium concentrations in

fields A, B and C had a large range with maximum values being highest in the A and C field

(55 and 137 mg/L respectively).

The potential for scale formation by silica species was notably more consistent across the

three CSG fields and for the range of water compositions of interest [Figures 22 to 24]. At no

instance did the scaling potential reach a value of 15 % and the variation in scaling potential

was typically less than 10 % across the water types examined. Silica has a solubility of 117

mg/L in water at a pH of 7 and temperature of 25°C [90]. It precipitates due to polymerization

in solution and therefore causes scaling of RO membranes [90, 129]. Silica is one of the most

complex species in water purification due to it complex structure [90, 92]. In this study the

feed water has a range of approximately 13 to 23 mg/L for fields A, B and C; however, it can

be shown that concentrations of silica in groundwater can be range from 40 to 100 mg/L [90,

129]. Cob et al. showed that fouling of RO membranes can be impacted as a function of

increased recovery rate with for example a recovery rate of 98 % as compared with 96 %

showing twice the thickness of a silica based deposit [90]. Milne et al. have shown that silica

fouling can be reduced by the following techniques: operating at a high pH with hardness

reduction, operating at a low pH, and use of pre-treatment techniques to reduce silica in the

feed water [92]. Pre-treatment techniques include chemical dosing with lime or aluminium

or iron salts, electrocoagulation, adsorption, or ion exchange [92].


© 2016 Page 82

Figure 22: Field A Scaling Potential ROSA Data

Figure 23: Field B Scaling Potential ROSA Data

Figure 24: Field C Scaling Potential ROSA data

The CS water was also simulated using IMS Design and the results are shown in Figures 25 to

27. In accord with the ROSA data, for each field and water composition there was minimal

suggestion of any scaling potential for calcium sulphate (< 5 %). With regards to silica species

IMS Design did not indicate any discernible scaling potential whereas ROSA suggested that

the scaling potential was ca. 10 % for all samples. Strontium sulphate had zero potential for

scaling for all three fields for the average CS water compositions, but did have a discernible

scaling potential for the minimum CS water compositions in fields A and C (26 and 30 %,

respectively). This result was inconsistent with the ROSA simulation which showed a

comparably small scaling potential for strontium sulphate (< 5 % for fields A, B and C).


© 2016 Page 83

Barium exhibited a high scaling potential in field A for the average, minimum and maximum

CS water compositions (91, 100, and 100 %, respectively) and field C for all compositions (100

%). However, the B field only showed 100 % scaling potential for the average and maximum

CS water concentration levels and a lower scaling percentage for the minimum CS water

composition (30 %). This result was not consistent with that of the ROSA simulation which

only showed a scaling potential for the maximum CS water composition. The prediction of

scaling for the maximum CS water composition is in accord with the relatively high

concentrations of both barium (2.32 to 9.38 mg/L) and sulphate present (5 to 48 mg/L). One

reason for the discrepancy in relation to the other water compositions may relate to the

possibility that the barium scaling potential can be overestimated depending on the method

used to calculate the supersaturation level [136].


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Figure 25: Field A Scaling Potential IMS Design Data

Figure 26: Field B Scaling Potential IMS Design Data

Figure 27: Field C Scaling Potential IMS Design Data


© 2016 Page 85

Calcium fluoride has been identified as a source for scaling potential in the IMS design

simulation for the average and maximum values for the A, B and C fields. The maximum CS

water sample universally showed a high scaling potential with 100 % for fields A, B and C. The

scaling potential for the average CS water composition was slightly lower for all 3 fields (67,

46, and 92 % for field A, B and C, respectively). Inspection of the ROSA data revealed that for

the minimum CS water compositions for each field the predicted degree of scaling potential

for calcium fluoride was in agreement with the IMS Design data; namely less than 10 % in

every case. In contrast, the discrepancy between simulations was apparent when examining

the scaling potential values for the average CS water composition in each field. IMS Design

predicted that the scaling potential ranged from 46 % (Field B) to 92 % for Field C, which were

considerably higher values compared to those resultant from application of ROSA (3.74 and

8.91 %, respectively). Magnesium hydroxide scaling potential was not calculated in the

simulation using IMS design as this calculation is not produced in this program.

The LSI for the simulations with both ROSA and IMS Design was found to be positive and

therefore there is the potential for scaling to occur. The higher the pH value the higher the

calcium and alkalinity concentrations and therefore the higher potential for calcium

carbonate scaling [109]. This latter situation is common in natural waters and the feed water

would need to be treated prior to treatment using RO, which was performed in both

simulations, ROSA and IMS design [91]. This was undertaken using acid addition which is one

way in which the LSI can be reduced [91]. As many variables change with acid addition it is

important to include this step prior to assessing the potential for scaling potential for other

compounds [91].

The simulations using two different commercially available software programs showed

slightly different results, with IMS design identifying a scaling potential for barium sulphate

for all the CS water types and a scaling potential for calcium fluoride for the maximum values

from each field. ROSA predicted that the average CS water compositions from each field

showed a scaling potential for calcium fluoride and the average and maximum for the C field

showed a scaling potential for barium sulphate. All the CS water in which a simulation was

undertaken with ROSA and IMS Design showed a scaling potential for calcium carbonate and

therefore the requirement for acid addition was clearly supported.

It has been found in the CSG industry that scaling of the RO membranes occurs from

compounds such as calcium carbonate, magnesium carbonate, magnesium hydroxide, and

calcium sulphate [62, 86]. Pre-treatment technologies such as ion exchange softening can


© 2016 Page 86

be used to reduce these compounds and therefore the potential for scaling of the

membranes [62, 86]. In this study the simulations showed a potential for calcium carbonate

scaling and this potential was adjusted with acid addition to lower the pH.

PRE-TREATMENT SELECTION

Barium sulphate and calcium fluoride have been shown to have a significant scaling potential

as evidenced by the simulations for the CS water in this study. Consequently, the application

of a suitable anti-scalant may be recommended [91, 109]. The anti-scalant used should be

carefully investigated as further problems can arise such as biofouling [136, 137]. A study by

Boerlage et al. based on the Amsterdam Water Supply RO Pilot Plant showed that in a

comparison between 2 different anti-scalants to mitigate barium sulphate, multiple factors

had to be taken into consideration including temperature, organic matter, recovery rate and

acid addition [136, 137]. The barium concentration of the feed water in this study was

significantly higher than that of the study conducted by Boerlage et al. (<10 and <0.09 mg./L,

respectively). Similar contrasts were shown in the sulphate concentration of the feed water

in the Boerlage et al. study which, was significantly higher than that in this study (<20 and

<80 mg/L, respectively).

Alternative options include effective cleaners for scale which remove mineral scaling,

colloidal particles or bio-foulants [62]. Solutions used are usually a combination of acidic

and/or basic chemicals and the technique is undertaken periodically when the permeate flow

decreases by >10 %, feed channel pressure loss increases by >15 % or normalised salt

rejection increases by 10 % [62]. Cleaning of the membranes increases overall performance

and recovery, however it can be an expensive technique and is not specific to a particular

compound as is the case with anti-scalants [62]. Due to economic pressure anti-scalants have

often been shown to be the preferred treatment method to assist in the performance of RO

plants [91, 109]. Chemical companies who manufacture RO membranes provide

assessments of each scalant or foulant that they produce and the options for pre-treatment.

An example from Filmtec is that for barium sulphate and calcium fluoride, where scale

inhibitor anti-foulant and softening with ion exchange are very effective; and dealkalization

with ion exchange and lime softening are possibly effective [91]. Ion exchange is well known

for its ability to soften water prior to an RO stage [74]. Either strong acid cation or weak acid

cation resins exchanged with sodium ions are employed to remove species such as calcium,

barium, magnesium, and strontium to acceptably low levels [30, 73, 75]. Lime softening can

also be employed to soften water prior to an RO stage, however, concerns have been raised


© 2016 Page 87

in terms of the issue of dealing with the produced lime sludge. Blaisi et al. [138] expressed

the caveat that care must be taken to ensure that lime sludge does not leach metals into the

environment. Cheng et al. [139] also cited issues in regards to the relatively large volume of

the lime sludge and also the fact that it is not readily dehydrated. As a consequence, they

added fly ash to the water in order to favourably modify the sludge properties.

Electrocoagulation has been demonstrated to exhibit effectiveness for removal of dissolved

alkaline earth ions from CS water [16]. Nevertheless, this technology has not been scaled up

to commercial levels as yet for this particular application and there are concerns relating to

the excessive consumption of electrode materials in the process due to non-Faradaic

processes such as corrosion by dissolved salts [16].

COMPARISON OF PERMEATE TO DRINKING WATER, IRRIGATION WATER

AND STOCK WATER TRIGGER VALUES

The following tables compare the values for the permeate water resulting from RO treatment

of CS water with trigger values for irrigation water and drinking water where the trigger is

that in which the water could no longer be used for the particular application.


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Table 14: Drinking Water and Irrigation Water Compared with Field A Permeate

Parameter Trigger

Value

Drinking

Water

Trigger

Value

Irrigation

Water

Permeate

Value

Average

Permeate

Value

Minimum

Permeate

Value

Maximum

Ammonium - - 0.057 0.021 0.245

Potassium - - 0.374 0.107 1.809

Sodium * 200 - 67.577 19.532 281.239

Magnesium - - 0.035 0.004 0.356

Calcium - - 0.83 0.009 16.697

Strontium - - 0.021 0.003 0.201

Barium 0.7 - 0.013 0.002 0.098

Carbonate - -

Bicarbonate - - 78.062 15.603 219.298

Nitrate 50 -

Chloride * 250 - 59.038 14.905 336.222

Fluoride 1.5 2 0.159 0.050 0.479

Sulphate - - 0.015 8.395 0.351

Silica - -

Boron ** 0.5 0.5 – 15 0.308 0.218 0.342

pH 6.5 – 8.2 6 – 8.5 7.4 6.7 8.1

Total

Dissolved

Solids

80 - 205.85 58.85 859.35

* Based on taste

** Depending on crop type

- No health impact or restriction level at maximum concentration level


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Table 15: Drinking Water and Irrigation Water Compared with Field B Permeate

Parameter Trigger

Value

Drinking

Water

Trigger

Value

Irrigation

Water

Permeate

Value

Average

Permeate

Value

Minimum

Permeate

Value

Maximum

Ammonium - - 0.062 0.021 0.182

Potassium - - 0.3 0.086 1.007

Sodium * 200 - 57.559 18.005 162.036

Magnesium - - 0.026 0.005 5.037

Calcium - - 0.058 0.014 0.327

Strontium - - 0.018 0.003 0.077

Barium 0.7 - 0.010 0.002 0.040

Carbonate - -

Bicarbonate - - 59.158 17.170 160.669

Nitrate 50 -

Chloride * 250 - 54.522 17.845 172.159

Fluoride 1.5 2 0.137 0.041 0.381

Sulphate - - 0.017 0.005 0.714

Silica - -

Boron ** 0.5 0.5 – 15 0.378 0.238 0.517

pH 6.5 – 8.2 6 – 8.5 7.3 6.6 7.9

Total Dissolved

Solids

80 - 172.32 53.44 504.71

* based on taste

** depending on crop type

- no health impact or restriction level at maximum concentration level


© 2016 Page 90

Table 16: Drinking Water and Irrigation Water Compared with Field C Permeate

Parameter Trigger

Value

Drinking

Water

Trigger

Value

Irrigation

Water

Permeate

Value

Average

Permeate

Value

Minimum

Permeate

Value

Maximum

Ammonium - - 0.095 0.026 0.343

Potassium - - 0.768 0.158 2.539

Sodium * 200 - 121.808 28.539 378.689

Magnesium - - 0.108 0.005 0.743

Calcium - - 0.321 0.016 11.901

Strontium - - 0.068 0.005 0.441

Barium 0.7 - 0.033 0.003 0.205

Carbonate - -

Bicarbonate - - 65.342 10.966 198.713

Nitrate 50 -

Chloride * 250 - 151.190 30.104 493.077

Fluoride 1.5 2 0.162 0.029 0.439

Sulphate - - 0.018 10.418 0.106

Silica - -

Boron ** 0.5 0.5 – 15 0.278 0.168 0.422

pH 6.5 – 8.2 6 – 8.5 7.3 6.7 7.9

Total Dissolved

Solids

80 - 340.28 80.44 1088.78

* based on taste

** depending on crop type

- no health impact or restriction level at maximum concentration level

The simulations suggested that boron, total dissolved solids and sodium did not always

comply with the regulations for drinking water and/or irrigation water. It has been shown in

the treatment of brackish water that boron can be difficult to remove [86, 126, 128]. The

comparison of the permeate quality of the CS water in this study to that of drinking water

compliance with World Health Organisation guidelines shows that the maximum values for

the permeate for the B and C fields do not satisfy regulations (<0.5 mg/L) [125]. The boron

concentrations in this study varied as shown in Figure 28, and the permeate concentrations


© 2016 Page 91

were similar to that of the feed water (concentration decrease ranging from 0.002 to

0.198mg/L).

Figure 28: Boron Concentration A, B and C Field

Therefore, it may also be necessary to employ a methodology to control boron levels in the

permeate [140, 141]. A commonly reported technical solution to this latter problem is the

application of selective resins [142-144]. Darwish et al. [145] demonstrated that the

presence of common competing ions in solution such as sodium, magnesium, chloride and

sulphate did not inhibit uptake of boron by the N-methyl-d-glucamine functional groups on

synthetic resin. The degree of boron removal from solution was relatively high (>80 % in

most instances) and was promoted by decreasing resin particle size, increasing contact time,

higher resin dose, higher temperature and an optimum pH of 8; in contrast, greater

concentrations of boron were more difficult to remediate. Korkmaz et al. [146] similarly

found that boron removal was not as efficient when boron concentrations were relatively

high (up to 1000 mg/L) and in this instance a pH of 8.5 was stated to be optimal. Nadav and

Koutsakos [147] described the integration of a boron selective ion exchange resin treatment

stage to purify the RO permeate resulting from desalination of 40,000 m3/day water in

Limassol, Cyprus.

The total dissolved solids in CS water can be highly variable as shown in this study with

concentrations ranging from ca. 2,000 to 10,000 mg/L [Figure 29]. It has been identified that

TDS can vary not only between CS water within the same seam but also between coal seams

[6, 65]. A pilot study undertaken by Nghiem et al. on CS water on from the Gloucester Basin


© 2016 Page 92

in New South Wales Australia, showed that the pre-treatment method using ultrafiltration

had no impact on the reduction TDS concentration and this was only reduced by RO and

multi-effect distillation (MED) [65]. Similarly the same study showed that no impact was

made on the conductivity of the CS water and this was only reduced again by the RO and

MED process [65]. The advantage of RO for use as a desalination technique is the lower

energy required as compared with thermal processes such as MED [98, 99]. The TDS

concentration of the permeate after simulation by IMS Design showed that it was still

significantly high when compared with Australian Drinking Water Quality Guidelines [117].

Figure 29: TDS Concentration A, B and C Field

The sodium concentration in permeate from this study has also been found to be above the

level required for Australian Drinking Water Quality Guidelines in A field and C field for

maximum concentration levels. Figure 30 shows the concentration of sodium for the CS

water from this study and it is shown that is considerably higher than that required for

drinking water (<200mg/L) prior to any treatment. This analysis has shown due to the large

concentration range not all of the sodium has been removed by the treatment of RO and is

present in the permeate above levels that can be used as set out in the Australian Drinking

Water Guidelines for the maximum concentration levels for field A, B and C (281, 162, and

378 mg/L, respectively) [117].


© 2016 Page 93

Figure 30: Sodium Concentration A, B and C Field

The treatment of brackish water by the process of RO and the pre-treatments such as

ultrafiltration, nanofiltration and ion exchange have seen an increase in CSG industry in

Australia which have been required due to the chemical composition of CS water [86, 148].

As a result, and the evaluation of the pre-treatment as well as the recovery, maintenance

and cost of the process of RO has been significant. Factors influencing the recovery of the

permeate can include feed composition and temperature, pre-treatment technologies,

chemical cleaning procedures, feed pressure, membrane type, and system configuration [62,

86, 148].

It appears that drinking water supply may not be the primary beneficial reuse option for CS

water due to the aforementioned difficulties with ensuring water quality always satisfies

guidelines. However, if we compare to standards for irrigation or stock watering for example

[Figures 31 & 32] it is evident that the permeate water quality is always compliant with these

less demanding applications.


© 2016 Page 94

Figure 31: Irrigation Water Drinking Water and Stock Water Trigger Level Sodium, Nitrate,

Chloride and TDS

Figure 32: Irrigation Water Drinking Water and Stock Water Trigger Level Barium and Boron

Chapter 8: Conclusions

© 2016 Page 95

7Chapter 8: Conclusions

It has been shown that the water chemistry of CSG water can be highly variable from well to

well and from field to field. Nevertheless, the general chemical composition and physical

properties (high pH, bicarbonate alkalinity (as CaCO3), Na+, Cl- and low Ca2+, Mg2+and SO42-)

were in accord with other CSG fields in Australia and the world. However, the depth of

information in this study provided new insights into the quality of CSG associated water, the

relationships between species present and the range by which key components can vary.

Although precise connections between the location of the well and water quality could not

be related to local geology, in general the water composition was consistent with the mineral

matter in the Surat Basin.

It was demonstrated that analysis and interpretation of large data sets using multivariate

analysis for water quality monitoring may be required by future monitoring programs. This

approach will be of benefit not only for legislators but also the CSG operating companies. It

was also demonstrated that a predictive tool using surrogate indicators can determine two

parameters of significance (SAR and TDS) in relation to beneficial reuse of CS water. The

predictive model developed was used not only to evaluate 150 CS water samples from the

Surat Basin but also previous studies from New Zealand, the US and the Bowen Basin in

Australia.

In light of the range of CSG water compositions identified it was pertinent to examine the

impact on the central desalination technology of reverse osmosis. It was found that the

outcomes of two commercial software packages for evaluating reverse osmosis technology

(ROSA and IMS Design) surprisingly did not always give comparable predictions. Hence, it is

recommended that both software packages are used to evaluate scaling potential of brackish

water and that the most “pessimistic” values be considered for each water type analysed. By

this latter approach, the safest treatment strategy can be selected.

Analysis of the various CS water compositions from the 3 CSG fields of interest revealed that

it may be necessary to soften the CS water prior to the RO stage as both calcium fluoride and

barium sulphate represented sources of concern with respect to potential scaling of


© 2016 Page 96

membranes and equipment. Consequently, the use of anti-scalant chemicals or an ion

exchange unit comprising of appropriate sodium exchanged synthetic resins was advised.

PRACTICAL IMPLICATIONS

The CSG industry although operating for 15 years in Australia still has a requirement to better

understand CS water characteristics and in turn select the optimal treatment process. The

comprehensive understanding of the variability of CSG associated water quality and the

relationship between these water quality parameters was therefore valuable. Significantly,

this study discovered that the water chemistry even changed depending upon the depth and

location of individual wells within a field. Hence, it is challenging to predict a relationship

between water quality and geological formation.

In turn, selection of appropriate treatment technologies for CS water needs to take into

account the wide range of values for dissolved species and physical properties such as

turbidity and pH. For example, high values of silicates in the CS water may demand additional

strategies such as use of anti-scalants to minimise fouling of equipment and downstream

membranes. As boron in CS water is difficult to remove by reverse osmosis, then selective

resins may also need to be employed.

The linear regression modelling that has been developed and presented is of significance for

the Queensland CSG industry as water quality parameters, such as SAR and TDS are required

to be reported prior to use or disposal of CS water. However, these parameters can only be

determined by laboratory testing. The large and relatively remote geographical area in which

the Surat Basin CSG industry operates, makes the time between water quality sampling and

receiving laboratory test results lengthy. As a consequence, this delay may result in

ineffective management of CS water, such as transferring it to holding dams rather than for

beneficial use. The application of a linear regression model to form a predictive equation

based on site water quality monitoring data should be taken into consideration prior to the

selection of the treatment option [78, 108]. This outcome can result in reduced financial cost

and prediction of the most effective treatment method and use for specific CS water.

FUTURE WORK

This work has identified that there is a need for large-scale water quality monitoring and

analysis of CS water in the Surat Basin in order to understand regional differences and ensure


© 2016 Page 97

that the most effective and efficient treatment technologies are being utilised. Multivariate

analysis could be used in future work, particularly if comparisons were required to be made

using large data sets. Large-scale water quality monitoring and analysis will aid in the

knowledge of chemical composition of the CS water from various areas within the Surat Basin

which will ensure that current legislative requirements and treatment technologies are

specific to the CS water that is being treated, and to the industry in which it is being re-used.

Future work would include the development of specific predictive models such as that

presented in this study for other basins in which the CSG industry operates. Future work

should also be directed towards laboratory studies of CS water desalination using reverse

osmosis membranes to confirm the predictions from this study.

References Page 98

© 2015 Page 98

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