1.0 introduction - rlms€¦ · oal seam gas (csg) from coal seams hosted within the betts creek...

Galilee Basin Report on the Hydrogeological Investigations

PR102603-1; Rev 1 / December 2012

1.0 Introduction

The Galilee Basin Operators’ Forum (GBOF) engaged RPS Australia East Pty Ltd (RPS) to prepare a baseline groundwater monitoring scoping study for the Galilee Basin in north-central Queensland (Figure 1.1). The activities of GBOF and this study are being coordinated by Resources and Land Management Services (RLMS).

The GBOF members propose to extract coal seam gas (CSG) from coal seams hosted within the Betts Creek beds and the Aramac Coal Measures.

1.1 Background

The Galilee Basin study area extends 700 km from Charleville in the south to near Charter Towers in the north and 550 km east to west from Emerald in the east to Julia Creek in the north-west. The Galilee basin covers approximately 247,000 km2. The basin is traditionally divided into a 164,000 km2

northern region and an 83,000 km2 southern region. Longreach is located to just south of the basin centre. Petroleum exploration tenements cover nearly the entire basin, but most active exploration being conducted by GBOF companies is occurring in the northern region (Figure 1.2).

Groundwater resources in the Galilee Basin study area are hosted in:

Shallow Quaternary alluvial aquifers;

Shallow Tertiary sediment and minor volcanic rock aquifers;

Eromanga Basin aquifers; and

Galilee Basin aquifers.

The near surface water-bearing strata, the shallow groundwater hosted in Quaternary alluvial and Tertiary sediments, are typically used locally for domestic water supplies and stock watering. The shallow groundwater hosted in Quaternary alluvial and Tertiary sediments typically do not yield large volumes of groundwater.

Groundwater use from the Eromanga aquifers is greatest in the populated eastern recharge zones. However, there is an area of groundwater use north of Longreach (Plate 1 and Plate 2 in Appendix A).

The depth of the Galilee Basin aquifers means that these aquifers are infrequently tapped for groundwater except where these aquifers subcrop under the thin Quaternary alluvium and Tertiary sediments in the eastern portion of the Galilee Basin study area. These aquifers are typically tapped as a source of domestic or stock water.

1.2 Galilee Basin Operators’ Forum

Because the Galilee Basin sediments and the overlying Eromanga Basin sediments both have broad stratigraphic continuity over a wide area, a series of energy companies with exploration interests in the region formed a group to support a cooperative and coordinated approach to defining the hydrogeology, identifying risks to groundwater resources and assessing groundwater monitoring requirements.


PR102603-1; Rev 1 / December 2012

Figure 1.1 Location of the Galilee study area


PR102603-1; Rev 1 / December 2012

Figure 1.2 Petroleum exploration tenement boundaries within the Galilee Basin study area


PR102603-1; Rev 1 / December 2012

This group, known as the Galilee Basin Operators’ Forum (GBOF), currently consists of the following organizations:

AGL Energy Limited;

Blue Energy Ltd;

Comet Ridge Ltd;

Exoma Energy Ltd;

Galilee Energy Ltd;

Origin Energy Pty Ltd;

Pangaea Galilee Pty Ltd;

Queensland Energy Resources Limited;

Resolve Geo Pty Ltd; and

WestSide Corporation Ltd.

1.3 Scope

The scope for RPS for this hydrogeological investigation was as follows:

Delineate aquifers that may warrant monitoring;

Meet with GBOF members to identify areas proposed to or likely to host CSG field development;

Obtain relevant data pertaining to stratigraphy of field areas from the GBOF members;

Review the Eromanga and Galilee Basin stratigraphy and identify possible aquifers in the Galilee Basin study area;

Review the identified aquifer sediments and identify the potential aquifers and water-bearing sediments lying above and immediately below the target CSG formations (Appendices B and C);

Identify formations in the study area that warrant monitoring;

Obtain and tabulate current Department of Environment and Resource Management Groundwater Database (DERM GWDB, 2010) registered bores data including:

» water bore location and summary statistics (Appendix B);

» groundwater levels (Appendix D); and

» groundwater quality (Appendix E).

Identify and tabulate available groundwater level data for subartesian bores (Appendix D);

Undertake a preliminary, coarse screening to attribute formations to subartesian water bores;

Identify flowing bores and tabulate available temporal data for flow including, if possible, piezometric level data;

Obtain from Department of Environment and Resource Management (DERM) details of its program for Great Artesian Basin (GAB) flowing bore re-measurement;

Obtain from DERM details of its data logger / tipping bucket rain gauge program for GAB outcrop areas;

Identify and tabulate baseline and regional changes in groundwater level, water bore production, water flows;

Undertake a preliminary, coarse screening to attribute formations to artesian water bores;


PR102603-1; Rev 1 / December 2012

Create time series groundwater level and discharge for key artesian bores;

Prepare graphs of available time series water level and discharge for key subartesian bores;

Review and tabulate groundwater quality across the basin and individual formations;

Prepare trilinear Piper diagrams of major ion water chemistry for each identified key formation;

Prepare tabulated simple statistics for key groundwater quality parameters (e.g. ranges, means) for each identified key formation;

Identify existing water bores to be included in a groundwater monitoring program;

Prepare, scope and estimate indicative costs to prepare a refined baseline groundwater-level monitoring program;

Provide documentation of project work; and

Document initial hydrogeological investigation in a report.

1.4 Overview of Galilee Basin study area exploration history

The first exploration well in the south-eastern Galilee Basin study area was spudded in 1922 over the Springsure Shelf (Figure 1.3). The Tambo 1 exploration well, drilled to explore for petroleum, penetrated to 365.8 m bGL (metres below ground level). The stratigraphy of the Tambo 1 well has not been captured in the Queensland Petroleum Exploration Database (QPED). The next exploration well spudded in the basin was Nive River 1 in 1924. Nive River 1 was also drilled over the Springsure Shelf to explore for petroleum. Nive 1 reached 353.6 m bGL and was recorded to penetrate to the Walloon Coal Measures and the Bandanna Group sediments. Note that Tambo 1 and the Nive River 1 have the earliest recorded spud dates in QPED (2011). There are, however, 34 exploration wells with lower bore numbers where the spud date is not available, so exploration of the area may predate 1924.

There was very little exploration activity between the 1920s and 1954 when Clive 1 was spudded. In 1960 the Magellan Petroleum Corporation drilled the Corfield 1 stratigraphic well. The term "Galilee Basin" was introduced by Whitehouse in 1955 (Whitehouse, 1955). Corfield 1 encountered the base of the Hutton Sandstone at 1,085 m bGL and basement sequence at 1,373 m bGL. Permian age sediments were penetrated but were not differentiated on the driller’s log. Corfield 1 was plugged and converted to a water bore, presumably tapping the Hutton Sandstone and shallower aquifers.

Alliance Oil drilled Jericho-1 in 1965 into the Palaeozoic basement. The first government stratigraphic reference bores, Jericho 4 and 5, were drilled by the Bureau of Mineral Resources (BMR) in 1966. All of the BMR bores drilled in the 1960s were less than 100 m deep. The first deep government stratigraphic wells, Tambo 1-1A, were drilled by the Geological Survey of Queensland in 1973. Exploration well, Tambo 1-1A, terminates in the Drummond Basin sequence at 2,704 m bKB.


PR102603-1; Rev 1 / December 2012

Figure 1.3 Structural provinces of the Galilee Basin study area


PR102603-1; Rev 1 / December 2012

To date the petroleum exploration programs completed in the Galilee Basin study area have not discovered commercial quantities of oil or gas in conventional reservoirs. However, oil and gas shows have been recorded in Lake Galilee 1 and Koburra 1 (Alan, 1974; Benstead, 1973; Hawkins, 1978, 1982; Vine, 1976; Evans, 1980; P.R.A.D.S., 1990). Oil was recovered in Lake Galilee-1 from the Lake Galilee sandstone. In Koburra-1 and Carmichael-1, gas was produced at rates too small to measure. Numerous lesser shows have been recorded in other wells and formations.

The first CSG well in the Galilee Basin study area was drilled into the Koburra Trough by Enron Exploration Australia (EEAPL) in 1993 (Figure 1.3). Following the drilling of Rodney Creek 1, EEAPL drilled seven additional exploration wells (Aberfoyle 1, Crossmore 1, Crossmore 2, Fleetwood 1, Splitters Creek 1, Rodney Creek 2 and Rodney Creek 3). Subsequent to the EEAPL drilling, Galilee Energy acquired the EEAPL authority and drilled four additional exploration wells, Rodney Creek 4 to 7. Galilee Energy established a pilot-testing program based on the Rodney Creek drilling but was unable to depressurise the target coal seams. Rodney Creek 8 was drilled to confirm CSG potential.

Current exploration work is targeting the potential CSG reserves in the extensive Permian coal measures that lie within the Galilee Basin study area. The current exploration work is also targeting the potential petroleum resources over the Maneroo Platform.


PR102603-1; Rev 1 / December 2012

2.0 Communication with GBOF members

The Galilee Basin hydrogeological investigation started with a meeting of GBOF company representatives and RPS on Thursday 2 December 2010. Following this initial meeting, RPS circulated a pro forma interview to systematically gather data on the activities within the active GBOF tenements.

The Galilee Basin groundwater investigation was designed to gather data from a range of public sources and to use those data to establish the current groundwater conditions in the Galilee Basin study area. The publicly available sources are sufficient to provide hydrogeological data on a basin-wide basis, but are not sufficiently detailed to provide a full baseline that is useful to the individual tenement holders in the Galilee Basin study area. The pro forma responses supplemented the publically available data with data collected as part of recent CSG exploration activities.

The pro forma was circulated by RPS to gather data, recently collected by the GBOF members, on the subsurface conditions, locations of aquifers, aquifer pressures and groundwater quality within the active tenements. As noted previously, the GBOF members have collectively drilled more than 30 exploration wells in the Galilee Basin study area where the full well completion reports have not yet been made public. The data provided by the GBOF members allowed RPS to incorporate this newly acquired data into the baseline assessment results presented in this report. Specifically, the data provided by GBOF members was used to establish groundwater quality and aquifer pressures within the Permian coal measures in more detail than would have otherwise been possible.

All of the GBOF members responded to the pro forma. The depth and details of the responses pro

forma reflected the degree to which the individual members had pursued exploration within their respective tenements.

The pro forma data gathering process was followed by a series of meetings with the individual GBOF members. RPS met with six of the GBOF companies between early December 2010 and late February 2011. These meetings provided an opportunity to transfer the project relevant data and to discuss project related issues and concerns. These meetings were extremely fruitful especially with regard to addressing project and data confidentiality. The discussions related to confidentiality informed how RPS managed the client data and the content of this report.

RPS provided GBOF with a project update in early March 2011. The project update provided a very useful opportunity for the GBOF to provide interim suggestions for improvements. The recommendation to map the distribution of subartesian and artesian bores and to map the water bores by attributed aquifer have been included in Section 6.0. The second recommendation, to assemble geological cross sections, is presented in Section 3.0.

Documenting the current conditions within the aquifer systems of the area covered by the Galilee Basin study area requires time series data on artesian bore flow and pressure (where available). This time series data are necessary to establish how current groundwater use is impacting the Eromanga and Galilee Basin aquifers within the project area. An assessment of the aquifer flow and pumping test data is presented in Section 6.3 and in individual tenements discussions.


PR102603-1; Rev 1 / December 2012

3.0 Review of stratigraphy and identification of possible aquifers in

region

3.1 Overview

The approximately 247,000 km2 Galilee Basin began to form in the Late Carboniferous when continental extension opened a large basin in Devonian and older sediments across north-eastern Australia. The extension created a large sedimentary platform that filled with the Galilee Basin sequence starting in the Late Carboniferous and ending in the Middle to Late Triassic (Hawkins, 1982). The surface geology, derived from the Queensland regional geology, is presented on Figure 3.1. The detail for the map symbols for Figure 3.1 are presented in Appendix F. A summary table that shows the relationships between the names used in this report and in the source data for this report is shown in (Table 3.1 and 3.2).

The following five major structural provinces have been identified within the Galilee Basin study area (Figure 1.3):

Adavale Basin (Auchincloss, 1976 and Paten, 1977);

Drummond Basin sequence (Olger, 1972 and Vine, 1972);

Mt Isa Inlier;

Cape River Province; and

Maneroo Platform.

The Adavale Basin, which is found beneath the south-eastern portion of the Galilee Basin study area, is an Early Devonian to Early Carboniferous age sequence of sediments and minor volcanics. The sediments and rocks of the Adavale Basin can be up to 8,000 m thick. The Early Carboniferous age Buckablie and Etonvale Formations, of the Adavale Basin, have been noted in drill logs from holes drilled near the south-eastern margin of the study area.

The basin limit is defined by the early Palaeozoic age Lolworth-Ravenswood Block to the north-east of the study area, and the early Palaeozoic age Maneroo Platform and Canaway Ridge to the south-east (Hawkins and Green, 1993). The south-eastern limit of the Galilee Basin is defined by the Springsure Shelf and Nebine Ridge in the far south-east (Figure 1.3).

The Late Devonian to early Carboniferous Drummond Basin sequence lies beneath the Koburra Trough portion of the Galilee Basin study area. The Early Carboniferous Natal and Star of Hope are the most frequently logged formations in boreholes that penetrate the Galilee Basin sequence into the Drummond Basin sequence. Occurrences of the Bulliwallah Formation have also been recorded.

The northern limit of the Galilee Basin is defined by several shallow basement blocks, including the Proterozoic Mount Isa Inlier. Bores tapping the Mt Isa Inlier are not recorded in the bores drilled in the eastern Galilee Basin study area. The northern Galilee Basin study area is bounded by the Early Palaeozoic metamorphic rocks of the Cape River Province. Rocks from the Cape River Province are not widely reported in the bores logs within the Galilee Basin study area.


PR102603-1; Rev 1 / December 2012

Figure 3.1 Map showing the surface geology of the Galilee Basin study area

Refer to appendix Table F-1 for geological legend


PR102603-1; Rev 1 / December 2012

Table 3.1 Galilee Basin stratigraphic relationships Basin Age Group Formation Member Correlatives, informal

names, or names not in common usage in area

Quaternary Alluvium

Tertiary undifferentiated sediments/basalt flows

Ero

man

ga B

asin

Cretaceous

Rolling Downs Group

Winton Formation

Mackunda Formation

Griman Creek Formation

Allaru Mudstone

Toolebuc Formation

Wallumbilla Formation

Coreena Member

Doncaster Member

Cadna-owie Formation

Wyandra Sandstone Member

Gilbert River

Formation

Bly

thes

dale

G

roup

Ronlow beds (2)

Hooray Sandstone Longsight Sandstone

Jurassic Injune Creek

Group

Westbourne Formation

Adori Sandstone

Birkhead Formation

Hutton Sandstone

Evergreen Formation Boxvale

Sandstone Member

Precipice Sandstone basal Jurassic; Poolowanna Formation

Gal

ilee

Basi

n

Triassic Moolayember Formation Warang Sandstone (2)

Clematis Sandstone Dunda beds

Rewan Formation

Permian Betts Creek beds Bandanna Formation

Black Ally Shale

Colinlea Sandstone

Late Carboniferous

to Early Permian

Joe Joe Group Aramac Coal Measures

Jochmus Formation Oakleigh Siltstone Member

Jericho Formation Edie Tuff Member

Lake Galilee Sandstone

Basement:Thomson Orogeny Metasediments, Drummond Basin or Adavale Basin sediments (1) Not to scale (2) Basin margin facies

Regionally significant sources of groundwater

Locally significant sources of groundwater


PR102603-1; Rev 1 / December 2012

The basement geology does not significantly interact with the hydrogeology of the Galilee Basin study area except where the Eromanga Basin occurs over the Maneroo Platform. The geology of the Maneroo Platform includes the Drummond Basin sequence. The Maneroo Platform is discussed separately because of the local contact between the Hutton Sandstone and the Permian coal measures along its northern boundary.

The relatively shallow Galilee Basin is generally divided into northern and southern regions by the east / west trending Barcaldine Ridge. Figure 1.3 shows location of the following three centres of deposition that have been defined for the Galilee Basin:

Lovelle Depression;

Koburra Trough; and

Powell Depression.

The Late Carboniferous to Middle Triassic age Koburra Trough opened first and is up to 2,800 m deep. The oldest Galilee Basin formations, the Joe Joe Group was deposited on the basement unconformity in the Koburra Trough (Figure 3.2). The shallower Lovelle Depression, which is only 730 m deep, is filled with Early Permian to Middle Triassic age sediments. The older Joe Joe Group formations are not found at the base of the Lovelle Depression (Figure 3.3 and Figure 3.4). The Powell Depression is filled with 1,700 m of Early Permian to Middle Triassic sediments.

The deposition of the Galilee Basin sedimentary sequence was interrupted by a period of erosion between the deposition of the Aramac Coal Measures and Betts Creek beds. There is an unconformity that formed between the Betts Creek beds and the Aramac Coal Measures. This unconformity occurs in the early Permian coal sequence and is an important stratigraphic marker within the Galilee Basin sequence (Figure 3.5). It can be used to locate where the Permian coal measures occur at depth and to define the Permian age coal measure outcrop and subcrop areas. We refer to this as the “Permian unconformity” in this report. The depth to, and the zero edge, of the Permian unconformity is presented on Figure 3.5.

Deposition ceased by the end of the Triassic and was followed by a period of erosion that removed a portion of the upper Galilee sedimentary sequence. The erosion was the greatest at the northern edge of the Maneroo Platform. This erosion exposed the Betts Creek beds and the Aramac Coal Measures, giving way to the deposition of the Eromanga Basin sediments directly on the Galilee Basin sediments. The resultant unconformity occurs at the base of the Jurassic sequence and this therefore referred to as the basal Jurassic unconformity.The basal Jurassic unconformity marks the transition between the Galilee Basin sequence and the overlying Eromanga Basin sequence. The depth to and the zero edge of the basal Jurassic unconformity are presented on Figure 3.6.


PR102603-1; Rev 1 / December 2012

Figure 3.2 Map showing the top of the Lake Galilee Sandstone.


PR102603-1; Rev 1 / December 2012

Figure 3.3 Geological cross section from A to A’ (See Figure 1.3)


PR102603-1; Rev 1 / December 2012

Figure 3.4 Geological cross section from B to B’ (See Figure 1.3)


PR102603-1; Rev 1 / December 2012

Figure 3.5 Map showing the Permian age unconformity (i.e. the contact between the Betts Creek beds and the Aramac Coal Measures)

kerissa.reedy

Rectangle

kerissa.reedy

Typewritten Text

Outcrop of the Permian age unconformity

kerissa.reedy

Typewritten Text

Contour lines of elevation of Permian age unconformity (m AHD)

kerissa.reedy

Typewritten Text

Populated places

kerissa.reedy

Typewritten Text

Rivers / creeks

kerissa.reedy

Text Box

Major roads

kerissa.reedy

Typewritten Text

GSQ mapped extent of Galilee Basin

kerissa.reedy

Typewritten Text

GBOF Tenements


PR102603-1; Rev 1 / December 2012

Figure 3.6 Map showing the buried portion of the Galilee Basin Sedimentary sequence (i.e. the basal Jurassic age unconformity)

kerissa.reedy

Rectangle

kerissa.reedy

Typewritten Text

Inferred outcrop of the Jurassic Age unconformity

kerissa.reedy

Typewritten Text

Contour lines of elevation of of the Jurassic age unconformity (m AHD)

kerissa.reedy

Typewritten Text

Populated places

kerissa.reedy

Typewritten Text

Rivers / creeks

kerissa.reedy

Text Box

Major roads

kerissa.reedy

Typewritten Text


kerissa.reedy

Typewritten Text

GBOF Tenements


PR102603-1; Rev 1 / December 2012

The zero edge of the Eromanga Basin sequence is located within the Galilee Basin study area in the north and east (Figure 3.6) and is defined by the major sedimentary basin bounding faults in the north and east. The deposition of the Eromanga Basin sediments on top of the Galilee Basin sediments marks a major shift in the location of the deposition centres. The Galilee Basin sediments were deposited in troughs and depressions local to the basin itself. The Eromanga Basin sediments were deposited into a very large basin where the centre of deposition is located over 500 km to the south-west, beyond the Queensland / South Australia border.

The Eromanga Basin and Galilee Basin sequences have been covered by relatively recent Tertiary sediments and local volcanics, and Quaternary alluvial sediments. These younger deposits are thin, relative to the underlying Eromanga Basin and Galilee Basin sequences, and typically occur near the major creek and river systems that drain the Galilee Basin study area. The younger deposits also cover much of the stable platforms in north-eastern Galilee Basin study area located east and west of the Great Dividing Range.

3.2 Galilee Basin study area

The Permian to Triassic age Galilee Basin sediments outcrop between the eastern edge of the Eromanga Basin sediments and the faulted margin of the Galilee Basin (Figure 3.5). The contact between the Drummond Basin sequence (i.e. Ducabrook Formation), and the Galilee sedimentary sequence are exposed along the south-eastern basin boundary over the Springsure Shelf. P.R.A.D.S. (1990) considers the Galilee Basin sequence to be continuous with the Bowen Basin sequence across the Springsure Shelf and Nebine Ridge. The Galilee Basin sequence may also be continuous with the Cooper Basin sequence across the Canaway ridge (P.R.A.D.S., 1990). These continuations, into the adjoining basins, are potentially important groundwater flow paths out of the Galilee Basin study area.

The Galilee Basin began to form when Late Carboniferous to Early Permian age crustal extension reactivated basement faults. Late Carboniferous age braided-channel fluvial sediments filled the Koburra Trough. The oldest formation, the Lake Galilee Sandstone, was deposited unconformably on the Drummond Basin sequence and Thomson Orogeny metasediments. Fluvial and lacustrine sediment deposition in the Galilee Basin persisted from the Late Carboniferous to Early Permian. The lower energy fluvial and lacustrine sediments of the Joe Joe Group were conformably deposited on Lake Galilee Sandstone (Table 3.2 and Figure 3.3). The deposition of the Joe Joe group progressed from the Jericho Formation to the Aramac Coal Measures near the top of the sequence.

The Aramac Coal Measures deposition terminated in the Early Permian as east to west compression resulted in a period of reverse faulting, uplift and erosion. The Betts Creek beds were deposited unconformably on the Aramac Coal Measures.

The deposition of the coal-bearing Betts Creek beds across the northern Lovelle depression and the Koburra Trough was accompanied by the deposition of the Colinlea Sandstone in the southern portion of the basin. The three major coal-bearing sequences, the Aramac Coal Measures, Colinlea Sandstone and Betts Creek beds were all deposited during the Permian. Groundwater is found within the coal measures and coarse strata within these three major coal-bearing sequences..


PR102603-1; Rev 1 / December 2012

Table 3.2 Galilee Basin stratigraphic variation in depositional-centres Basin Age Lovelle Depression Koburra Trough Powell Depression

Quaternary Alluvium

Tertiary undifferentiated sediments

Erom

anga

Bas

in

Cretaceous Winton Formation Winton Formation Winton Formation

Mackunda Formation Mackunda Formation Mackunda Formation

Allaru Mudstone Allaru Mudstone Allaru Mudstone

Toolebuc Formation Toolebuc Formation Toolebuc Formation Wallumbilla Formation

(Coreena Member, Doncaster Member)

Wallumbilla Formation (Coreena Member, Doncaster Member)

Wallumbilla Formation (Coreena Member, Doncaster Member)

Cadna-owie Formation Cadna-owie Formation Cadna-owie Formation

(Wyandra Sandstone Member)



Hooray Sandstone Hooray Sandstone Hooray Sandstone

Jurassic Westbourne Formation Westbourne Formation Westbourne Formation

Adori Sandstone Adori Sandstone Adori Sandstone

Birkhead Formation Birkhead Formation Birkhead Formation

Hutton Sandstone Hutton Sandstone Hutton Sandstone

Evergreen Formation Evergreen Formation Evergreen Formation

(Boxvale Sandstone Member)



Precipice Sandstone Precipice Sandstone Precipice

Sandstone/Warang Sandstone

Gal

ilee

Bas

in

Triassic Moolayember Formation Moolayember Formation Moolayember Formation

Clematis Sandstone Clematis Sandstone Clematis Sandstone/Dunda beds

Rewan Formation Rewan Formation Rewan Formation

Permian

Betts Creek beds Betts Creek beds

Bandanna Formation

Black Alley Shale

Colinlea Sandstone

Late Carboniferous

to Early Permian

Aramac Coal Measures correlatives Aramac Coal Measure Not present

Jochmus Formation correlatives Jochmus Formation Jochmus Formation

Jericho Formation Jericho Formation Jericho Formation

Not present Lake Galilee Sandstone Not present

Basement Thomson Orogeny Metasediments Drummond Basin Adavale Basin

Locally Significant Sources of Groundwater

Regionally Significant Sources of Groundwater


PR102603-1; Rev 1 / December 2012

Fine-grained low permeability strata, such as mudstone, siltstone and shale, are interspersed within Aramac Coal Measures, Colinlea Sandstone and Betts Creek beds.

Sedimentation during the Late Permian and Triassic concentrated in the north-eastern part of the basin as the depositional area of the Galilee Basin contracted. Westerly to south-westerly draining rivers deposited the Rewan Formation sediments on the Betts Creek beds during the Early Triassic. The deposition of the Rewan Formation was followed by a period of uplift and the subsequent deposition of the Middle Triassic Clematis Sandstone and Moolayember Formation.

Uplift and gentle warping during the Late Triassic ended major sedimentation in Galilee Basin study area. The deposition of the Eromanga Basin sediments was preceded by early Jurassic erosion and subsequent down warping.

3.3 Eromanga Basin

A large crustal depression formed over a large extent of north-eastern Australia during the Late Triassic and early Jurassic, setting the stage for the deposition of the Eromanga Sediments (Wecker, 1989). This depositional surface is the regionally significant basal Jurassic unconformity, which separates the older Galilee Basin sediments from the younger Eromanga Basin sediments (Figure 3.2 and Figure 3.6).

The Eromanga Basin sedimentary sequence is defined vertically by the subcrop with the overlying Tertiary sediments and Quaternary alluvium and laterally by the basal Jurassic unconformity (Figure 3.4 and Figure 3.5). The outcrop of the basal Jurassic unconformity defines the northern limit of the Eromanga Basin Formation sequence within the Galilee Basin study area. The southern extent of the Eromanga Basin is located south of the Queensland / South Australia border. The Eromanga Basin sediments that overlie the Galilee Basin sediments were derived from two distinct source materials. The Eromanga Basin sediments from the east were derived from dominantly volcanic and sedimentary source materials. The Eromanga Basin sediments from the west were derived from dominantly metamorphic and granitic materials (van Heeswijck, 2004) with some additional volcanic and sedimentary source materials. The Evergreen Formation (including the water-baring Boxvale Sandstone Member) and the Precipice Sandstone and equivalents are deposited at the base of the Eromanga Basin sedimentary sequence.

The Ronlow beds were deposited on the Warang Sandstone (i.e. Evergreen Formation) during the Early Jurassic to the Early Cretaceous. The fluvial to lacustrine Hutton Sandstone, Birkhead Formation, Adori Sandstone, Westbourne Formation and Hooray Sandstone were deposited in the large thermal crustal depression. The shallow marine Wyandra Sandstone member of the Cadna-owie Formation was deposited on the Hooray Sandstone. The Wyandra Sandstone is overlain by the thick shallow marine mudstones of the Rolling Downs Group (Figure 3.7). The end of marine sedimentation is marked by deposition of the transitional Mackunda Formation and deposition of the non-marine sediments of Winton Formation.

The most recent stratigraphic unit is the Rolling Downs Group, which outcrops at the surface across the Maneroo Platform. The base of the Rolling Downs Group is shown on Figure 3.7. The zero edge of the Rolling Downs Group is located approximately 30 km west of the basal Jurassic unconformity,


PR102603-1; Rev 1 / December 2012

which defines the eastern limit of the Eromanga Basin inside the Galilee Basin study area. The Rolling Downs Group formations, the Winton Formation, Mackunda Formation and the Allaru Mudstone, outcrop extensively across the northern and western Galilee Basin study area (Figure 3.1). The Wallumbilla Formation, the base of the Rolling Downs Group, underlies these formations.

The significant Eromanga Basin aquifers, the Hooray Sandstone, the Cadna-owie Formation and the Hutton Sandstone underlie the Rolling Downs Group. The Winton Formation and Rolling Downs Group sediments also host important small-scale groundwater supplies. These sediments outcrop along the basal Jurassic unconformity in the north and the east. The Injune Creek Group sediments lie between the Hooray Sandstone and the Hutton Sandstone. Groundwater is produced from the Adori Sandstone and the coal measures within the Injune Creek Group sediments, which are separated by fine-grained low permeability strata. The often thick Westbourne Formation is a regionally significant aquitard.

3.4 Groundwater

Groundwater quality in the Galilee Basin study area is generally good. The Eromanga and Galilee Basin aquifers generally yield water of sufficient quality for livestock and in some instances for domestic use without requiring water treatment (Hawkins, 1992). The Hutton Sandstone (i.e. Eromanga Basin) and Clematis Sandstone (i.e. Galilee Basin) host significant groundwater resources with regards to the volume of available groundwater and the suitability of the groundwater quality for domestic and stock watering use. The Great Artesian Basin is composed of the Eromanga Basin aquifers and the upper Galilee Basin aquifers (GABCC, 1998). The contact between the Clematis Sandstone and the underlying Rewan Formation marks the lower boundary of the GAB sequence.

Pressure data available for the Joe Joe Group aquifers indicates that the Betts Creek beds and Aramac Coal Measures are capable of confining groundwater. However, the extensive coarse-grained fluvial beds in the Betts Creek beds and Aramac Coal Measures mean that these units are unlikely to be effective aquifer seals on a regional basis (DEEDI, 2009). The Bandanna Formation and the Black Alley Shale confine the Colinlea Sandstone. The Rewan Formation confines the groundwater that occurs within the Betts Creek beds and Aramac Coal Measures and the Moolayember Formation confine the underlying Clematis Sandstone aquifer. These aquifers, where they are tapped, are accessed in the eastern portion of Galilee Basin study area where these aquifers subcrop beneath thin Quaternary alluvium and Tertiary sediments at shallow depths.

There is significant artesian pressure in some of the Eromanga Basin and Galilee Basin aquifers and groundwater is documented to flow at the surface from bores tapping aquifer from depths exceeding 900 m (Holland et al., 2008).

A search of the DERM GWDB (2010) found that most significant exploited groundwater resources in the Galilee Basin study area lie within the shallow Eromanga Basin sequence and are the Hutton Sandstone, Hooray Sandstone, and Cadna-owie Formation. Significant groundwater resources are also produced from the aquifers hosted by the relatively shallow Rolling Downs sediments. Useable volumes of groundwater are also found in the alluvial deposits associated with the major rivers and some Tertiary sediments and local volcanics.


PR102603-1; Rev 1 / December 2012

Figure 3.7 Map showing the base of the Rolling Downs Group

kerissa.reedy

Rectangle

kerissa.reedy

Typewritten Text

Contour lines of elevation of of the base of the Rolling Downs Group (m AHD)

kerissa.reedy

Typewritten Text

Populated places

kerissa.reedy

Typewritten Text

Rivers / creeks

kerissa.reedy

Text Box

Major roads

kerissa.reedy

Typewritten Text


kerissa.reedy

Typewritten Text

GBOF Tenements

kerissa.reedy

Typewritten Text

Approximate extent of the Rolling Downs Group


PR102603-1; Rev 1 / December 2012

3.4.1 Pressure gradient

RPS derived a pressure gradient across the Galilee Basin study area of 7.2 kPa/m (1.04 psia/m) based on Pressure Plot 2.0 developed by CSIRO. The pressure gradient data are presented on Figure 3.8. DEEDI (2009) derived a higher pressure gradient of 9.8 kPa/m (1.42 psia/m) for the Galilee Basin study area stratigraphy using four exploration wells in Koburra Trough and three from the southern Galilee Basin study area (Figure 1.3). DEEDI (2009) estimate that this pressure gradient is equivalent to a head of approximately 300 m Australian Height Datum (AHD) or very near the average elevation of the intake beds. The Galilee Basin study area groundwater intake beds are located along eastern basin margin. The RPS gradient yields a head that is approximately 150 m AHD or somewhat below the intake bed surface elevation, which is slightly below the mean groundwater levels for these Galilee Basin aquifers. The difference in these results is attributed to using data from the entire basin, which includes the shallower aquifer systems that are not recharged along the higher elevation of the Great Dividing Range.

Groundwater levels and aquifer pressures are discussed in more detail in Section 6.2.

3.4.2 Temperature gradient

RPS derived a temperature gradient for the Galilee Basin study area of 2.9 ºC/100 m (Figure 3.9). DEEDI (2009) examined a very small dataset for the southern Galilee Basin study area and derived a much higher temperature gradient of 4.0 ºC/100 m. The DEEDI (2009) relationship, which was developed using extrapolated borehole bottom hole temperature, is higher than the RPS values or the temperature gradients of 2.95 ºC/100 m and 2.46 ºC/100 m at Aramac 1 and at Hexham 1, respectively, measured by Hawkins (1975). Comet Ridge calculated temperature gradients for 74 wells, with a range of 1.99 to 5.97 ºC/100 m, average of 3.77 ºC/100 m. Therefore, high temperature gradients are a feature of the study area.

3.4.3 Alluvial aquifers

Shallow unconfined groundwater is found in the alluvial deposits along the major river systems and creeks that drain the Galilee Basin study area. DERM attributes over 1,400 water bores as tapping the alluvium within the Galilee Basin study area (Figure 3.1). Groundwater levels in bores tapping range from 0 to 45.7 m bGL.

3.4.4 Tertiary sediment and basalt aquifers

Tertiary sediment aquifers host some appreciable individual supplies with both subartesian and artesian characteristics on the eastern margin of the area Galilee study area. Tertiary age basalts also host appreciable groundwater supplies in some areas where the volcanics occur. The DERM GWDB (2010) records more than 200 bores screened in or open to Tertiary age aquifers.


PR102603-1; Rev 1 / December 2012

Figure 3.8 Pressure / Depth relationship for the Galilee Basin study area

Figure 3.9 Temperature / Depth relationship for the Galilee Basin study area

3.4.5 Eromanga Basin aquifers and aquitards

3.4.5.1 Rolling Downs Group

The Rolling Downs Group sediments host the upper unconfined aquifers within the Galilee Basin study area. The Rolling Downs Group includes the following formations in the study area:

Winton Formation;

Mackunda Formation;

Allaru Mudstone;

Toolebuc Formation; and

Wallumbilla Formation (including the Coreena Member and Doncaster Member).

Galiliee final shut in pressures

0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

4,500

5,0000 1,000 2,000 3,000 4,000 5,000 6,000 7,000

Pressure (psia)

Dep

th (m

bK

B)

y = 0.0294x + 23R2 = 0.5196

0

20

40

60

80

100

120

140

160

180

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

Depth (m b GL)

Tem

pera

ture

(°

C)

TemperatureLinear (Temperature)


PR102603-1; Rev 1 / December 2012

Overall, the Rolling Downs Group is composed of a grey mudstone, siltstone and fine sandstone, and minor glauconitic sandstone; locally hardened and partially grey clayey calcrete regolith interpreted as slaked unstable mudstone. A slake mudstone will disaggregate when exposed at the surface. Air and rainwater will cause slake mudstones to erode rapidly.

The upper Rolling Downs Group formations, the Cretaceous age Winton and Mackunda Formations host subartesian aquifers that are tapped by nearly 1,900 bores in the Galilee Basin study area. Both the Winton and Mackunda Formations outcrop extensively in the Lovelle Depression, over the Maneroo Platform, and in the Powell Depression (Figure 3.1).

The Winton Formation outcrops across much of the western basin margin. The Winton Formation, which can be up to 1,200 m thick (Geoscience Australia, 2011), is composed of lithic and feldspathic sandstone, mudstone, siltstone and minor conglomerate. Local occurrences of lignite coal and volcanic detritus within this formation are known. The average depth to the top of the water-bearing strata in this formation is over 75 m b GL with an estimated average saturated thickness of 6 m, as indicated in the Australian Natural Resources Atlas (2011). This value for a saturated thickness is likely to be an underestimate. The Mackunda Formation, which can be up to 275 m thick, is composed of feldspathic sandstone and siltstone. The average depth to the top of the water-bearing strata is nearly 180 m b GL with an estimated average saturated thickness of 6 m (Australian Natural Resources Atlas, 2011). Groundwater from the Winton Formation has an average salinity of 2,792 mg/L based on total dissolved solids (Appendix E). Groundwater from the Mackunda Formation has an average salinity of 2,032 mg/L based on total dissolved solids (Appendix E).

Although considered to be a major aquitard, the Allaru Mudstone is the locally important source of groundwater. The Allaru Mudstone comprises primarily blue-grey mudstone and interbedded calcareous siltstone, cone-in-cone limestone and lesser sandstone. It can be up to 700 m thick.

At depth the subartesian aquifers of the upper Rolling Downs group give way to fine-grained sediments of the Cretaceous age Toolebuc and Wallumbilla Formations. These formations form a confining layer between the upper Rolling Downs subartesian aquifers and the underlying confined Cadna-owie Formation aquifers. The Toolebuc Formation, which can be up to 65 m thick, is composed of limestone, calcareous bituminous shale and coquinite. The Toolebuc Formation outcrops in a narrow east-west oriented band at the top of the Lovelle Depression and in a north-south oriented band just north of the western end of the Barcaldine Ridge (Figure 3.1).

Although the Wallumbilla Formation, which is up to 600 m thick, is a confining unit, more than 150 bores are open to its Coreena Member and nearly all bores are open to its Doncaster Member in the Galilee Basin study area. The Coreena Member of the Wallumbilla Formation, which can be up to 165 m thick, is composed of siltstone and fine sandstone interbedded with mudstone. The Doncaster Member of the Wallumbilla Formation, which is up to 275 m thick, is composed of mudstone, siltstone, minor quartz sandstone (in part glauconitic), silty limestone, and gypsum. The Wallumbilla Formation sediments sporadically outcrop though the overlying formations and alluvium along a 10 to 15 km wide arc beginning in the north-west corner of the Galilee Basin study area and ending near the transition between the Koburra Tough and the Springsure Shelf (Figure 3.1). The base of the Rolling Downs Group is presented on Figure 3.1. Much of the eastern extent of the Wallumbilla Formation is buried beneath the Quaternary alluvial sediments.


PR102603-1; Rev 1 / December 2012

3.4.5.2 Cadna-owie Formation

The transitional Cadna-owie Formation, which can be up to 900 m, underlies the Wallumbilla Formation. In the study area the Cadna-owie Formation is composed of non-marine to marine sandstones, siltstone, calcareous sandstone and pebbly sandstone (Australian Geosciences, 2011). The DERM GWDB (2010) indicates that the Cadna-owie Formation is tapped by fewer than 30 bores. Locally, the Cadna-owie Formation is dominated by the Wyandra Sandstone Member of the Cadna-owie Formation, which outcrops near the north-eastern and eastern limits of the Koburra Trough (Figure 3.1).

The Wyandra Sandstone Member is dominantly medium to coarse grained quartzose to sublabile sandstone, with scattered pebbles and carbonate cement. The sandstone is porous and permeable and is stratigraphically the highest major aquifer in the Great Artesian Basin. It ranges in thickness from 3 to 18 m. It is widespread in the central part of the Eromanga Basin in Queensland and extends into South Australia and New South Wales.

3.4.5.3 Hooray Sandstone and correlatives

The Hooray Sandstone and its correlatives host major confined aquifers within the Eromanga Basin sequence. The correlatives of the Hooray Sandstone which represent basin margin facies include:

Longsight Sandstone;

Blantryre Sandstone;

Gilbert River Formation; and

Ronlow beds.

The Late Jurassic to Early Cretaceous age Hooray Sandstone can be up to 400 m thick, and is composed of quartzose and lithic sandstone, siltstone, conglomerate, mudstone and coal. Isolated outliers of the Hooray Sandstone equivalents, the Ronlow beds and the Gilbert River Formation occur.

The Ronlow beds is an informal name for a sandy basin-margin facies, which comprises quartzose to sublabile sandstone, minor siltstone, mudstone and coal. The Gilbert River Formation is composed of clayey quartz sandstones and some sublabile and glauconitic sandstones, and may be locally bioturbated.

3.4.5.4 Injune Creek Group

The Injune Creek Group sediments underlie the Hooray Sandstone.

The Injune Creek Group is composed of calcareous lithic sandstone, siltstone, mudstone, coal, and conglomerate and in the study area is differentiated into the Westbourne Formation, the Adori Sandstone and the Birkhead Formation (Table 3.2). The Late Jurassic age Westbourne Formation, which can be up to 220 m thick, is composed of fine-grained sandstone interbedded with siltstone, claystone and minor coal. The Westbourne Formation potentially confines the underlying Adori Sandstone. The DERM GWDB (2010) bore records indicate that more than 160 bores are open to the Injune Creek Group in the study area. The Adori Sandstone, which can be up to 55 m thick, is


PR102603-1; Rev 1 / December 2012

composed of fine-to medium-grained clayey sandstone and minor pebbly sandstone and siltstone. The Birkhead Formation, which may be up to 110 m thick, underlies the Adori Sandstone, and comprises fine-grained sandstone, siltstone and carbonaceous mudstone. The Injune Creek Group overlies the Hutton Sandstone.

The major component formations of the Injune Creek Group and the Hooray Sandstone equivalents outcrop in an approximately 20 km wide north-west to south-east band overlying the Springsure Shelf (Figure 3.1).

3.4.5.5 Hutton Sandstone

The Early to Middle Jurassic age Hutton Sandstone, which can be up to 290 m thick, is composed of poorly sorted, coarse to medium-grained, feldspathic sublabile sandstone (at base) and fine-grained, well-sorted quartzose sandstone (at the top); minor carbonaceous siltstone, mudstone, coal and rare pebble conglomerate. The DERM GWDB (2010) indicates that the Hutton Sandstone is tapped by more than 600 water bores in the study area. The Hutton Sandstone outcrops to the east of the Injune Creek Group sediments.

3.4.5.6 Evergreen Formation

The Early to Middle Jurassic age Evergreen Formation, which can be up to 255 m thick, is composed of labile and sublabile, sandstone, carbonaceous mudstone, siltstone and minor coal and local oolitic ironstone. The Boxvale Sandstone Member of the Evergreen Formation is the portion of this formation that hosts usable volumes of groundwater in some areas in general and the study area specifically. The Boxvale Sandstone Member of the Evergreen Formation is composed of clean, fine-medium grained quartz sandstone and fossil wood. Both the Evergreen Formation and Boxvale Sandstone Member outcrop over a comparatively small area in the south-eastern corner of the study area (Figure 3.1).

3.4.5.7 Precipice Sandstone

The earliest Jurassic sediments tend to be either absent or not differentiated from the overlying Hutton Sandstone in the study area. Where present, the Early Jurassic Precipice Sandstone is a thick-bedded, cross-bedded, pebbly quartzose sandstone, with minor lithic sublabile sandstone, siltstone, and mudstone, which can be up to 200 m thick. The Precipice Sandstone outcrops over the Springsure Shelf in a narrow north-west to south-east trending band. Elsewhere the basal sediments may be called Poolowanna beds (more commonly in use in South Australia) or simply “basal Jurassic”.

The Eromanga and Galilee Basins are separated by a disconformity or erosional surface that marks the end of the major sedimentation in the Galilee Basin study area (Figure 3.6).


PR102603-1; Rev 1 / December 2012

3.4.6 Galilee Basin study area aquifers and aquitards

3.4.6.1 Moolayember Formation, Clematis Sandstone, Rewan Formation and correlatives

The Middle Triassic age Moolayember Formation contains the uppermost sediments of the Galilee Basin sequence. The Moolayember Formation, which can be up to 315 m thick, is a confining bed and is composed of micaceous lithic sandstone and micaceous siltstone. Small isolated outcrops of this formation occur through the overlying younger sediments found along the eastern margin of the Koburra Trough. The contact with the underlying Clematis Sandstone is gradational in the northern portion of the Galilee Basin (McKellar, 1977).

The Early to Middle Triassic age Clematis Sandstone, which can be up to 130 m thick, consists of medium to coarse-grained quartzose to sublabile, micaceous sandstone, siltstone, mudstone and granule to pebble conglomerate. The DERM GWDB (2010) indicates that the Clematis Sandstone aquifer is tapped by more than 100 water bores in the Galilee Basin study area. The Clematis Sandstone outcrops though the younger sediments in a similar pattern to the Moolayember Formation.

In the Koburra Trough, the Clematis Sandstone is underlain by the Dunda beds, which are correlative with the upper Rewan Formation. The Dunda beds are composed of lithic to quartzose sandstone, siltstone and mudstone. The Dunda beds are recognized to be the upper facies of the Rewan Formation in the outcrop areas, which lie to the east of the Clematis Sandstone outcrops. The DERM GWDB (2010) indicates that nearly 20 water bores in the study area are open to the Dunda beds.

The contact in the central Galilee Basin study area between the Clematis Sandstone is gradational (Olgers, 1970) and erosional in the southern Galilee Basin study area (Exon, 1970 and Senior, 1973).

The Warang Sandstone, which can be up to 700 m thick, is correlative to the lower Moolayember Formation and Clematis Sandstone. The Warang Sandstone is correlative to the Clematis Sandstone in the northern Galilee Basin study area (van Heeswijck, 2004). The Warang Sandstone is a kaolinitic quartz sandstone, conglomerate, variegated mudstone and siltstone. The Warang Sandstone outcrop is similar to the outcrop pattern of its correlative formations.

The Warang Sandstone is evident in the eastern outcrop areas of the Koburra Trough where it grades into the formations to the west. West of the Maneroo Platform, the Warang Sandstone facies dominate the Moolayember Formation and Clematis Sandstone sequence in the Lovelle Depression. The Warang Sandstone conformably overlies the Betts Creek beds. However, Vine (1964) records a disconformable contact at the Hughenden 1/2R well.

The Early Triassic age Rewan Formation, which can be up to 840 m thick, consists of lithic sandstone, pebbly lithic sandstone, green to reddish brown mudstone and minor volcanolithic pebble conglomerate (at base). The Rewan Formation was deposited in a fluvial-lacustrine environment and is a regionally significant confining unit.


PR102603-1; Rev 1 / December 2012

3.4.6.2 Betts Creek beds and correlatives

The Late Permian age Betts Creek beds, which are approximately 100 m thick, are composed of conglomerate and sandstone at the base, with siltstone, mudstone, and coal seams present towards the top. The coal seams within the Betts Creek beds represent the major target formation for the GBOF members. The Betts Creek beds outcrop area is small and is confined to the northern extent of the Koburra Trough at the basin boundary (Figure 3.1). The Betts Creek Beds subcrop under the Hutton Sandstone north of the Hulton-Rand structure, which marks the start of the Maneroo Platform (Figure 3.4 and Figure 3.5).

In the south east, the Bandanna Formation, Black Alley Shale, Peawaddy Formation and Colinlea Sandstone can be traced over the Springsure Shelf from the Bowen Basin into the Galilee Basin; and these formations have been recognised in petroleum wells in that region. These formations are age-correlatives of the Betts Creek beds, which is widely recognised in the north of the basin. (van Heeswijck, 2006).

Available regional mapping data indicates that the Colinlea Sandstone, which can be up to 300 m thick but averages 70 m (QPED, 2011), is composed of quartz sandstone, pebbly quartz sandstone, minor conglomerate and siltstone (Australian Geosciences, 2011). The Colinlea Sandstone is an unconfined aquifer near the outcrop areas located along the north-eastern extent of the Galilee Basin deposits overlying the Springsure Shelf (Figure 3.1) and confined elsewhere.

The Bandanna Formation, which consists of calcareous lithic sandstone, siltstone and coal with minor tuff and oil shale (van Heeswijck, 2006), is not mapped to outcrop in the Galilee Basin study area.

3.4.6.3 Joe Joe Group

The Late Carboniferous to Early Permian Joe Joe Group is composed of tillitic conglomerate, lithic sandstone, siltstone, minor mudstone and coal and comprises the formations:

Aramac Coal Measures;

Jericho Formation;

Jochmus Formation; and

Lake Galilee Sandstone.

The Joe Joe Group sediments can be up to 1,250 m thick. All of the component formations have been logged in the bore holes drilled in the Koburra Trough, with the Aramac Coal Measures and Jochmus Formation being logged in the Lovelle Depression. The Joe Joe Group sediments outcrop at the Galilee Basin study area boundary over the Springsure Shelf.

The Betts Creek beds and correlative formations unconformably overlie the Aramac Coal Measures in the Lovelle Depression and both the Aramac Coal Measures and Joe Joe Group in the Koburra Trough. The Aramac Coal Measures are restricted to the northern surface of the Barcaldine Ridge and the Lovelle Depression (Hawkins and Green, 1993). This unconformity correlates with the New


PR102603-1; Rev 1 / December 2012

England Orogeny to the east of the Galilee Basin study area. The Aramac Coal Measures subcrop under the Hutton Sandstone north of the Hulton-Rand structure, which marks the start of the Maneroo Platform (Figure 3.4 and Figure 3.5).

The Late Carboniferous age Lake Galilee Sandstone is the basal formation of the Galilee Basin sequence. The Lake Galilee Sandstone, which can be up to 260 m thick, is composed of quartzose sandstone, minor conglomerate with argillaceous beds near the formation top. There are no known outcrops of the Lake Galilee Sandstone. However, the Lake Galilee Sandstone was logged in the Mogga 1 exploration well in the north-eastern part of the basin at 5.4 m bGL. Mogga 1 is located near the Galilee Basin margin where Joe Joe Group and Drummond Basin sequence have been mapped in close proximity at the surface. The well completion report for Mogga 1 refers to the Lake Galilee Sandstone as the Galilee Sandstone. The well completion report does not contain definitive evidence that this is the Lake Galilee Sandstone. However, the surrounding outcrops suggest that the Lake Galilee Sandstone could lie at a shallow depth in this area. Given this interpretation is unconfirmed, the depth to the Lake Galilee Sandstone at Mogga 1 has not been included on Figure 3.2

3.5 Identification of key aquifers within potential areas of operation areas

that could warrant monitoring

The aquifers that may require monitoring during CSG extraction vary considerably across the Galilee Basin study area. Variables which may determine monitoring requirements include:

The depth to the coal measures which changes laterally across the basin;

The thickness of the sediments between the coal measures and the surrounding aquifers;

The extent and location of coal measures. It is noted that the Permian age Betts Creek beds and Aramac Coal Measures, which are the Galilee Basin study area CSG targets, are absent over the Maneroo Platform;

Aquitard thickness, specifically the thickness of the Rewan and Moolayember Formations;

Areas where aquifers are in direct contact with the Betts Creek beds and Aramac Coal Measures; and

The location of CSG activities.

3.5.1 Quaternary alluvial and Tertiary sediment aquifers

Data from the DERM GWDB (2010) indicates that the shallow unconfined groundwater hosted in the Quaternary alluvium and Tertiary basalt and sediment aquifers are tapped by largest number of bores in the Galilee Basin study area. This is clearly an important source of groundwater in the Galilee Basin study area. Of the DERM recorded water bores which RPS could attribute to an aquifer, 25% were attributed to the Quaternary alluvial and Tertiary sediment aquifers. There are comparatively few bores drilled in the Tertiary age basalt, especially when compared to the Quaternary alluvium and the Tertiary sediment aquifers.


PR102603-1; Rev 1 / December 2012

Much of the Quaternary alluvial and Tertiary sediment aquifer materials have been deposited on the Winton Formation or other Rolling Downs Group sediments. However, in the north-east, the Betts Creek beds and Aramac Coal Measures subcrop beneath the Quaternary alluvial and Tertiary sediment aquifers. Given that the Betts Creek beds and Aramac Coal Measures potential outcroppings are buried, it is not possible to define clearly the contact area with the overlying younger sediments. However, the Permian unconformity location presenting on Figure 3.6 suggests where the Permian coal measures lie at a shallow depth. That is the Betts Creek beds and Aramac Coal Measures subcrop under the Quaternary alluvial and Tertiary sediment aquifers. An examination of the water bore density in the north-east Galilee Basin study area suggests that this is an area of significant groundwater use (Appendix A: Plate 1 and Plate 2). This means that the potential Permian CSG targets that will be depressurised to promote gas flow are potentially in direct contact with the shallow Quaternary alluvium aquifers and the surficial Tertiary sediment aquifers. The surficial aquifers directly overlying the Permian CSG targets may require monitoring should this portion of the Galilee Basin study area contain a viable CSG resource. However, this monitoring may require newly drilled bores because of the difficulty of identifying the aquifer a specific bore taps in existing bores.

3.5.2 Eromanga Basin aquifers—over the Maneroo Platform

Exploration well logs and water bore logs suggest that the Hutton Sandstone lies unconformably on the basement rocks and is very thin over the Maneroo Platform (Figure 3.4). The Hutton Sandstone also directly underlies the Birkhead Formation, which is a confining unit. The Adori Sandstone overlies the Birkhead Formation. The full Eromanga Basin sequence, stratigraphically above the Hutton Sandstone, is also present over the Maneroo Platform (Figure 3.4).

3.5.3 Eromanga Basin aquifers—over the Galilee Basin study area

Typically, the Eromanga Bsin aquifers, in particular the Hutton Sandstone , are not in direct hydraulic connection with the Permian coal measures (Figure 3.3, Figure 3.4 and Figure 3.10). The Moolayember Formation, which is a regionally significant confining unit, and the Clematis Sandstone usually form the interburden between the Hutton Sandstone and the Permian coal measures. This sometimes thick sequence of formations suggests that the depressurising of the Permian coal measures is unlikely to influence groundwater in the Hutton Sandstone aquifer. Depressurising the Permian coal measures is also unlikely to influence the Hooray Sandstone and Cadna-owie Formation aquifer systems, which lie stratigraphically above the Hutton Sandstone, and are separated from the coal measures by significant thicknesses of sediments.

Groundwater abstraction from the coal measures, although unlikely to impact any aquifer, has some potential to impact the Hutton Sandstone aquifer in certain situations. Therefore, the groundwater in the Hutton Sandstone may need to be monitored in particular situations where the aquifer is in contact with the coal measures, or an aquifer connection is suspected. This should be assessed on a case-by-case basis. Along the northern edge of the Maneroo Platform, the Moolayember Formation, Clematis Sandstone and Rewan Formation are at times not present between the Hutton Sandstone and the Permian coal measures. The Hutton Sandstone and the overlying Hooray Sandstone and Cadna-owie Formation aquifers system may need to be closely monitored if local depressurisation of the Permian coal measures is proposed in this area. The zero edge presented on Figure 3.10 provides a clear guide as to where the monitoring density need will likely be the greatest.


PR102603-1; Rev 1 / December 2012

Additional monitoring of the shallow formations should be considered on a case-by-case basis where potential aquifer interconnections are suspected.

3.5.4 Galilee Basin study area aquifers

The Galilee Basin sedimentary sequences aquifers are not tapped over much of the study area due to their depth below ground level and because alternative shallower groundwater sources are available. There are, however, some converted exploration wells drilled in the deeper Galilee Basin aquifers, but these are relatively few in number. The Galilee Basin aquifers are tapped where they occur at a shallow depth, generally in the north and eastern portions of the study area.

The following Galilee Basin aquifers may occur in contact with or may be stratigraphically close to the Permian coal measures:

Warang Sandstone;

Clematis Sandstone;

Dunda beds; and

Jochmus Formation (Upper Joe Joe Group).

The relative stratigraphic position of the Galilee Basin aquifers is illustrated in (Table 3.2). Groundwater monitoring may be required in the above formations in areas near active Permian coal measure depressurisation, once that occurs.

In the eastern subcrop areas, local groundwater abstraction occurs from the Moolayember and Rewan Formations as well as the Betts Creek beds, the Aramac Coal Measures and their correlatives. Therefore, there may be a local need to monitor groundwater in these formations where CSG production is/will be occurring.

There is extensive development of thermal coal resources underway in the belt of Permian coal measures between Alpha and Pentland. The coal measures will be dewatered to support mine developments (Figure 1.2). The dewatering of these coal measures has the potential to impact the Colinlea Sandstone. The coal mine dewatering will be extensive and could potentially extend to locations within the Galilee Basin study area where GBOF members may eventually produce CSG. CSG producers may choose to monitor groundwater between the coal mines and the CSG targets to identify and quantify cumulative impacts. In addition to collecting groundwater-monitoring data, the GBOF members could review and tabulate current DERM Great Artesian Basin (GAB) flowing bore data, paired groundwater data logger, and rain gauge information in the area between the coal mines and the Galilee Basin study area CSG activities. It is important to note that the coal mines will have their own requirements on the management and monitoring of dewatering required during mine development.


PR102603-1; Rev 1 / December 2012

Figure 3.10 The inferred interburden thickness between the base of the Hutton Sandstone and the underlying Permian coal measures

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Typewritten Text

kerissa.reedy

Rectangle

kerissa.reedy

Rectangle

kerissa.reedy

Typewritten Text

GBOF Tenements

kerissa.reedy

Typewritten Text

Interpolated boundary of potential Hutton Sandstone Zero Edge

kerissa.reedy

Typewritten Text

Interpreted area of potential ZERO Hutton to Permian separation

kerissa.reedy

Typewritten Text

Separation > 150m 50m < separation > 150m Separation <50m

kerissa.reedy

Typewritten Text

Isopach lines of separation distance between Hutton Sst and Permian age coal measures (m)

kerissa.reedy

Typewritten Text

Approximate outcrop of base of Hutton Sst

kerissa.reedy

Typewritten Text

Galilee Basin


PR102603-1; Rev 1 / December 2012

4.0 DERM program for groundwater data logger / tipping bucket

rain gauge program for GAB outcrop areas

DERM maintains a network of rain gauges paired with water bores to monitor groundwater level response to rainfall across the Great Artesian Basin (GAB) intake beds. The GAB intake beds outcrop across the north, east and over the Springsure Self in the Galilee Basin study area (Figure 3.1). GAB aquifer intake beds outcropping in the Galilee Basin study area include aquifers from the Eromanga Basin and the Galilee Basin sequence. The rain gauge / groundwater level monitoring bore sites are presented on Figure 4.1.

DERM provided RPS with tipping bucket rain gauge and averaged groundwater level data from the sites located within the Galilee Basin study area. RPS analysed the data from the following locations:

600305A - Paired with DERM GWDB Bore RN 330007;





600313A - Paired with DERM GWDB Bore RN 100330013; and

600308A - Paired with DERM GWDB Bore RN 330004.

The rain gauges are located close to a groundwater bore. Therefore, it is possible to compare changes in groundwater level with the changing rainfall levels. The close proximity of the gauge and the bore makes it possible to draw conclusions regarding changes in rainfall and the elevation of groundwater table. There are no data in the DERM GWDB (2010) regarding groundwater pumping near the paired rain gauges and bores. Therefore, there are insufficient data available to determine if groundwater pumping is influencing the hydrographs presented in Figure 4.2.

The paired rain gauge / groundwater level data are available from 1993 to 2010, with the exception of two gauges attributed to the Ronlow beds (i.e. 600306A and 600314A), where the data are only available from 2006 to 2008.

RPS plotted the rainfall data and the groundwater level data for each pair site on the same graph to determine the relationship between rainfall and groundwater recharge. Groundwater levels rarely respond to short-term changes in rainfall that occur over days to weeks. The changes in groundwater level were plotted against the mass residual rainfall curve (i.e. trace of cumulative deviations from long-term mean monthly rainfall). The mass residual rainfall curves presented on Figure 4.2 were derived from the tipping bucket rain gauge paired with a water bore. The residual rainfall is used because it represents long-term trends in rainfall, which are more closely linked groundwater recharge rates than the short-term daily or weekly rainfall depths. The mass residual curve presents the change in rainfall relative to the average. Residual rainfalls sloping downward to the right represents below average rainfall and residual rainfalls sloping upward to the right represents above average rainfall.


PR102603-1; Rev 1 / December 2012

Figure 4.1 Locations of DERM tipping bucket rain gauges and associated DERM GWDB bores


PR102603-1; Rev 1 / December 2012

Figure 4.2 Hydrographs showing DERM GWDB bore groundwater levels plotted against residual rainfall

(a)DERM Rainfall tipping gauge 600305A (DERM GWDB bore RN 330007 - Hooray Sandstone)

(b)DERM Rainfall tipping gauge 600309A (DERM GWDB bore RN 100320002 - Ronlow beds)

(c)DERM Rainfall tipping gauge 600306A (DERM GWDB bore RN 100320001 - Ronlow beds

(d) DERM Rainfall tipping gauge 600314A (DERM GWDB bore RN 100330014 - Ronlow beds)


PR102603-1; Rev 1 / December 2012

Figure 4.2 (cont.) Hydrographs showing DERM GWDB bore groundwater levels plotted against residual rainfall

(e) DERM Rainfall tipping gauge 600312A (DERM GWDB bore RN 100330012 - Injune Creek Group)

(f) DERM Rainfall tipping gauge 600313A (DERM GWDB bore RN 100320013 - Hutton Sandstone)

(g) DERM Rainfall tipping gauge 600308A (DERM GWDB bore RN 330004 - Hutton Sandstone)


PR102603-1; Rev 1 / December 2012

Using data from the DERM GWDB (2010), RPS was able to attribute the water bores to the following Eromanga Basin aquifers:

Hooray Sandstone;

Ronlow beds;

Injune Creek Group; and

Hutton Sandstone.

An analysis of the hydrographs found that groundwater levels at three paired sites responded to changing rainfalls as indicated by the mass residual curves.

The hydrograph for tipping gauge 600305A, attributed to the Hooray Sandstone, exhibits an increase in groundwater level of 0.11 m between February 1993 and June 2010. The record indicates a series of groundwater level recharge responses to rainfall. However, the correlation between mass residual curve and groundwater level change are not particularly close. There was an increase in groundwater levels corresponding to an increase in residual rainfall between 1993 and 1998. However, between 1998 and 1999 groundwater levels declined during a period of above average rainfall. The reason for the deviation is not known. Groundwater levels also rose from 1999 to 2001, during a period of decreasing residual rainfall. From 2001 to 2010, groundwater levels indicate relative correlation with residual rainfall. The lack of a close correlation between the mass residual rainfall and groundwater level changes may be due to current groundwater pumping from the Hooray Sandstone, which predates major CSG developments.

The hydrograph for tipping gauge 600306A, attributed to the Ronlow beds, exhibits an increase in groundwater level of 0.42 m between September 2005 and March 2007. The hydrograph for this site indicates an increase in groundwater levels with an increase in residual rainfall between 2005 and 2007. However, the correlation is not close.

The hydrograph for tipping gauge 600313A, attributed to the Hutton Sandstone site exhibits a decrease in groundwater level of 0.53 m between July 1995 and May 2009. The hydrograph for this site indicates some increase in groundwater levels with increasing residual rainfall between 1995 and 1996 and decreasing groundwater levels with decreasing residual rainfall between 1996 and 1997. However, increasing residual rainfall corresponds with a decrease in groundwater levels between 1997 and 2001; indicating possible external influences on groundwater levels, prior to major CSG development. There is further correlation between residual rainfall and groundwater levels between 2001 and 2009 where the groundwater levels and residual rainfall both decrease.

An analysis of the hydrographs found that groundwater levels at four pair sites show little or no response to changing rainfalls as indicated by the mass residual curves.

The hydrograph for tipping gauge 600309A, attributed to the Ronlow beds, exhibits a decline in groundwater level of 0.54 m between July 1995 and August 2010. This hydrograph exhibits almost no correlation between groundwater levels and residual rainfall, as groundwater levels remain consistent between 1995 and 2010 with the exception of anomalous (and potentially unreliable) groundwater levels between 2004 and 2005.


PR102603-1; Rev 1 / December 2012

The hydrograph for tipping gauge 600314A, attributed to the Ronlow beds, exhibits a decline in groundwater level of 0.25 m between September 2005 and May 2009. The lack of correlation in groundwater levels and the residual rainfall between 2005 and 2009 suggests that rainfall over this period did not result in groundwater recharge to this aquifer.

The hydrograph for tipping gauge 600312A, attributed to the Injune Creek Group, a subset of the Ronlow beds, exhibits 0.16 m decline in groundwater level between July 1995 and May 2009. The relatively constant groundwater levels between 1997 and 2009, a time when residual rainfall increases and decreases, suggests that rainfall and groundwater recharge are not linked. However, between 1995 and 1997 groundwater levels responded to changes in the residual rainfall. The relatively stable groundwater levels at this site suggest this aquifer does not respond to rainfall or drought.


PR102603-1; Rev 1 / December 2012

5.0 Springs in the Galilee Basin study area

The location of the nearly 500 distinct springs recorded for the Galilee Basin study area are presented on Figure 5.1. The springs plotted on Figure 5.1 were obtained from the Springs of Queensland Dataset Version 4.0. There are detailed data for the 265 springs that have been classified as either recharge, discharge or water course springs.

Of the 265 classified springs within the Galilee Basin study area, 38 springs are in the Barcaldine Region and the remaining 227 are located in the Springsure Region. The majority of the GAB springs are active (192) and only a small number have been bored or dammed. DERM does not maintain a database of springs that are not classified as a Great Artesian Basin spring.

There are two types of springs presented on Figure 5.1; recharge springs and watercourse springs. This discussion addresses the recharge springs only. Recharge springs are springs that occur in or near aquifer recharge areas. In this instance, we are addressing springs located in the GAB intake beds. Recharge springs occur because groundwater entering the intake beds re-emerges before recharging the deeper sections of the aquifer. The groundwater flow path between the source area and discharge area of a recharge spring is relatively short. The watercourse springs are important sources of groundwater discharge to GAB aquifers. In the Galilee Basin study area, the only watercourse springs relevant to this investigation are located on the southern edge of the Springsure Shelf. The watercourse springs occurring in an area identified as a groundwater discharge area are unlikely to be impacted by the possible CSG development since they are located a great distance from the active GBOF tenements (Figure 5.1).

The distribution of the springs over the intake beds suggests that groundwater is discharging in part from the Eromanga Basin or Galilee Basin aquifers via recharge springs within the Galilee Basin study area.

The aquifer from which the springs derive their water has not been recorded against the relevant spring in the Springs of Queensland Dataset. However, the distribution of the springs presented on Figure 5.1 gives a strong indication of which aquifer systems are feeding the springs, which are almost all located in the intake beds of the Eromanga Basin aquifers north of Barcaldine and the Galilee Basin aquifers over the eastern Springsure Shelf. The springs in the Galilee Basin study area are thought to be associated with shallow occurrences of the host aquifer sediments and not regional faulting. This assessment will need to be confirmed in the field.

The springs north of Barcaldine are located just west of the Hutton Sandstone zero edge (Figure 3.10). No springs occur west of the first outcropping of the Toolebuc Formation and possibly the Wallumbilla Formation.


PR102603-1; Rev 1 / December 2012

Figure 5.1 Map showing the location of the springs within the Galilee Basin study area


PR102603-1; Rev 1 / December 2012

The springs north of Barcaldine occur in two distinct bands, one that is likely associated with the Hutton Sandstone aquifer and one that is likely associated with the Cadna-owie Formation / Hooray Sandstone aquifer system:

Average discharge has been calculated at 6.35 L/s;

Lowest discharge has been recorded as 24 L/d (litres per day);

Highest discharge has been recorded as 199 L/s; and

Two registered springs were recorded as having no flow.

The Springsure Shelf springs are clustered near the eastern basin boundary on the edge of the shelf. These springs occur very near a series of Clematis Sandstone outcrops. This outcropping of the Clematis Sandstone is bounded by the overlying Moolayember Formation and underlying Rewan Formation. Although the highest flow recorded at an individual spring is in the Barcaldine group, the springs on the Springsure Shelf are generally more productive than the Barcaldine springs:

Average spring discharge was recorded at 27 L/s;

Lowest discharge has been recorded as 1 L/d;

Highest discharge has been recorded as 12.9 L/s; and

No flow was recorded at 72 registered springs.

1.0 introduction - rlms€¦ · oal seam gas (csg) from coal seams hosted within the betts creek...

Documents