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Integrated assessment of deep

sedimentary structures

Exploring groundwater resources in

the Perth Basin, Western AustraliaMike Trefry, CSIRO


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Acknowledgements

Thanks to the PERUMIN organizers!

CSIRO Minerals Down Under (MDU) Flagship

Colleagues in the Western Australian Geothermal

Centre of Excellence


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WAGCoE Colleagues

Klaus Regenauer-Lieb (Director), Nick Timms, Cedric Griffiths, Lynn Reid, Soazig Corbel,

Thomas Poulet, Ludo Ricard, Oliver Schilling, Heather Sheldon, Florian Wellmann,

Lionel Esteban, Jean-Baptiste Chanu, Paul Wilkes, Grant Douglas, Anna Kaksonen,

Dan Lester, Guy Metcalfe, Lucas Pimienta, Sebastian Gutbrodt, Stephanie Tressler,

Gemma Bloomfield, Cody Evans, Ali Karrech, Claudio Delle Piane, Remi Alix, Frank

Horowitz, Moyra Wilson, Katy Evans, Laura Sttenbecker, Shankar Israni, Joseph

Hamilton, Patricia Cope, Chris Dyt, Xiu Huang, Jacob Hopkins, David Champion,

Hugo Olierook, Steve Reddy, Brendan Florio, Dariush Nadri, Joel Sarout, Hui-Tong

Chua, Alex Christ, Peter Whittaker, Oliver Gaede, Christoph Schrank, Jie Liu, Lucy

Leyland, Len Baddock, Klaus Gessner, Liam OBryan, Libby Colgan, Tom Beckerling,

Allison Hortle, Sarah Glasson, JJ Leong, William Tran, Nathan White, Susan

Lissiman, Dylan Irvine, Aspasia Kouhsen, Cate Walker, Andrew Minto, Chris

Botman, Kristina Kazakoff, Lisa Miotti, Stephane Francois-Lubin, Guillaume Pons,

Charlotte Dos Santos, Sunil Varma, Sean Webb, Margaret Pryor, Melina Ielati


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Genesis

Western Australian Geothermal Centre of Excellence (2009-2012)

Tasked to map out hydrothermal resources in the Perth Basin of Western

Australia, down to 3 km depth and deeper

Developed an integrated geosciences workflow suitable for

mapping/characterizing groundwater, hydrocarbons and heat reservoirs

www.geothermal.org.au/Research.htm
http://www.geothermal.org.au/Research.htmhttp://www.geothermal.org.au/Research.htm


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Outline

1. Water in mining basic context

2. Groundwater fundamentals

3. Integrated groundwater assessment in the Perth

Basin

4. Lessons to share


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1. Water in Mining


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Water in Mining

Water is fundamental to miningused for heating, cooling,

dust suppression, processing and treatment

Water budgets are critical to below-ground and above-ground

operations (in situ recovery operations rely on groundwater) Too much water, or too little, is a big problem

Managing water quality throughout the mine life is key to

efficient mining

Water is a major vector for environmental impact


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Managing Water

Too much water iron ore mining in the Pilbara Mining is moving below the water table

60 GL/year fresh water to be produced (by one company)

Long way from population centres


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Providing Water

Not enough waterEscondida in the Atacama Groundwater supply is under stress

$3B seawater desalination plant to be built (2500 L/s)

Pipeline 160 km from the coast to the mine (+3 km altitude)


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Responsibility

Major mines need water strategy plans

A plan should show how a mine will operate profitably and

responsibly in cooperation with neighbouring water users

Strategies must be informed by sound understandings of thelocal and regional hydrological resources

Groundwater is always problematic!

Where? How deep?

How much is there? Is it useable? What is the water quality?

Is it replenished?


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2. Groundwater Fundamentals


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Basic Terminology

Aquifer: a geological formation that yields water when

pumped

Groundwater: water that resides in an aquifer

Porosity: amount of void space per unit volume of aquifer Permeability: measures the connectedness of pore spaces

Recharge: the rate of groundwater replenishment to an

aquifer, e.g. from rainfall.


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Aquifer Systems

Good Aquifer: high porosity/permeability and suitable water quality

Bad Aquifer: low porosity/permeability or unsuitable water quality

Unsustainable Aquifer: total groundwater loss exceeds the total recharge

Aquifer systems

can be complex

livingwatersmart.ca/water-act/groundwater.html
http://livingwatersmart.ca/water-act/groundwater.htmlhttp://livingwatersmart.ca/water-act/groundwater.htmlhttp://livingwatersmart.ca/water-act/groundwater.htmlhttp://livingwatersmart.ca/water-act/groundwater.html


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3. Integrated Groundwater

Assessment in the Perth Basin


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Sedimentary Basins in WA


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Perth Basin

Perth Basin is a deep (>10 km) half-graben feature filled with

sediments

Provides water for 90% of WA population

Groundwater resources below 1 km depth are largely

unexplored

Over-use of groundwater in the top 1 km, plus a drying

climate

Future industrial and urban development requires a sound

understanding of natural groundwater resources


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GW Resource Definition

Sufficient Volume Porosity

Geological structure / architecture

Sufficient flow Recharge

Permeability structure

Sufficient water quality Rock mineralogy Fluid geochemistry

Environmental conditions

Interrelated!


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Aquifer permeability

Shallow formations

Data GapsPerth Basin architecture


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Building on the Past

How can we explore the deeper resources in the Perth Basin?

An integrated study approach

Compile, collate and QA/QC existing data

Build a quantitative basin geomodel using all the data

Assess uncertainties (structural, parametric)

Recommend future investigations to minimize geomodel

uncertainty


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Basic Approach

Data sources

Hydrogeological reports and water well data

Petroleum/gas exploration drilling logs and cores

Geophysics (gravity, aeromagnetics, seismics)

Surface geology DEM topography and bathymetry

Depth to basement maps

Previous structural models

a new structural model


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Legacy Data

Well data coverage


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Integrating Data


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Refine and Iterate

Calibration

Cross-validation


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Faculty of Science and EngineeringDepartment of Applied Geology

Assemble Structures


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Inspect Structures


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Populate!

Now we have an improved structural model, we need ...

Hydrogeological reports and water well data

Petroleum/gas exploration drilling logs and cores

Geophysics (gravity, aeromagnetics, seismics)

Surface geology

Sedimentology (depositional environment)

Petrophysics (rock properties)

Geochemistry and mineralogy

a new property model


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Faulting


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New Interpretations

Integrated fault interpretations


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Fault Properties


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Wide range of lithofacies types

Consistent with fluvial

depositional systems

Faculty of Science and EngineeringDepartment of Applied Geology

Yarragadee

Formation

Cattamarra

Coal Measures

Eneabba

Formation

Lesueur

Formation

Lithologies


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Fine Stratigraphy

Heavily layered lithologies

Long sequences of fluvial

depositional processes


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Mineral Occurrence


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Poro-Perm


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Forward Models

Forward Stratigraphic

Modelling with SEDSIM


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Simulated Perms

Calibrated SEDSIM results

For the Yarragadee Formation


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Basin-Scale Model

First whole-of-Basin

property model


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High-Resolution

Perth

Vertical exaggeration

x10

Superficial

Aquifer

Leederville

Aquifer

Yarragadee

Aquifer

Perth metroproperty model


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Reservoir Analysis

Proposed faults

correlate with

groundwater

temperature @ 250 m


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Uncertainty

Quantify structural

uncertainty via entropy

measures


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Exploration Targets

Identify maximum

uncertainty in competing

structural models


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Summary

Re-analyzed legacy data sets

New geophysical data acquisition campaigns

Integrated, calibrated and cross-validated

New 3D structural and property models for Perth Basin

Easy computations of aquifer locations, volumes and

properties

Quantified uncertainty using entropy measures

Identified targets for subsequent investigation


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4. Lessons to Share


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Lessons to share

Seismic studies can be expensive and difficult in populatedareas

Deep exploration drilling/coring may require more expensive

drilling technology than shallow groundwater drilling Maximize the benefit of existing data by re-analyzing with

modern tools

Multidisciplinary approaches can help

Do the thinking before committing to major capitalexpenditure on exploration


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Muchas Gracias!

Mike Trefry

Minerals Down Under Flagship

[email protected]


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