Assessing potential impacts on water and the environment from shale, tight and deep coal gas development in the Cooper GBA region
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Hi, I'm Kate Holland from CSIRO, and I'm here to talk about the impact assessment for the Cooper GBA region. In the past four years, about a 100 scientists from CSIRO and Geoscience Australia have worked with regional communities and stakeholders. We've also collaborated with experts from our technical peer-review group, and the state and Commonwealth governments. Our work provides a comprehensive baseline to help decision-makers from government and industry to better understand where to look more closely and where risks are of low concern when they're assessing development proposals in the future.
The GBA program started in 2017 and consists of three stages. In stage one, we identified which basins were more perspective for gas. Three basins were selected, the Cooper Basin in Queensland and South Australia, the Beetaloo Sub-basin in Northern Territory, and the Isa Superbasin in Queensland. In stage two, we compiled existing information in a geological and environmental baseline assessment for each region. This helped identify knowledge gaps for field and modelling investigations in stage three. In stage three, we also developed and tested a new method, a spatial causal network to support future decision-making. In stage one, the Cooper Basin was ranked highest in terms of both the prospectivity and confidence, reflecting the extensive exploration and development over more than 50 years. In stage two, three unconventional gas play types that are prospective in the Cooper GBA region were identified, shale gas, basin-centred tight gas, and deep coal gas. These occur in three major troughs shown by the white circles on the map. The Nappamerri, Patchawarra, and Windorah troughs.
The Allunga and Wooloo troughs near Moomba are also prospective. This is consistent with the location of recent unconventional gas play exploration activity. A review of groundwater data in stage two found that 90% of bores were less than 300 metres deep. These bores access water from Cenozoic aquifers in the Lake Eyre basin, the yellow layer on the cross-section, and Winton-Mackunda aquifers at the top of Eromanga Basin, the khaki layers, which are part of the Great Artesian Basin. You can see that the Y-axis goes down five kilometres below the surface to the bottom of the Nappamerri trough. At the surface, Cooper Creek supports the Ramsar-listed Coongie Lakes and other waterholes and terminal lakes. Waterholes are sustained by localised freshwater lenses and recharged by floods. Surface water is an unreliable water source. Groundwater and produced water are the likely water sources for a future shale, tight and deep coal gas industry. Potential hydrological connections between deep unconventional gas plays or water source aquifers and environmental assets including groundwater-dependent ecosystems were identified for investigation in stage three.
In stage two, we identified 181 protected matters in the Cooper GBA region. This includes 70 species, and 111 areas protected under the EPBC Act, and state legislation in Queensland and South Australia. In stage three, the assessment prioritised 12 of these protected species, four birds, three mammals, and five plants based on the importance of the Cooper GBA region to each species. Most of the Cooper GBA region, more than 80%, is classified as floodplain and alluvium, inland dune fields, or undulating country on fine-grained sedimentary rocks. Conceptual models for each landscape class underpinned the assessments in stage three.
In stage two, we also identified hazards and reviewed existing evidence related to drilling and hydraulic chemicals, as well as hydraulic fracturing and compromised well integrity in greater detail. Over 200 individual hazards were systematically identified by considering all the possible ways an activity may impact on ecological, economic, and social values. The screening of 116 chemicals used for drilling and hydraulic fracturing of shale, tight, and deep coal gas wells between 2011 and 2016 found that 42 chemicals were of low concern, and so pose minimal risk to aquatic ecosystems. A further 33 chemicals were of potentially high concern, and 41 were of potential concern. Finally, the review of nine domestic and international inquiries into onshore gas industry operations and historical Cooper Basin data found that the likelihood of hydraulic fracture growth into an aquifer, a well, or a fault is low. The review also found that regulated construction of wells for shale, tight, and deep coal gas development activities ensure that fluid and gas are prevented from flowing unintentionally from the reservoir into another geological layer or to the surface.
In stage three, we developed and tested this spatial causal network for the Cooper GBA region based on the conceptual models, hazards, and protected matters, we identified in stage two. Essentially, we've broken the assessment into lots of little questions, the links in the network. The evidence to support our evaluations of the likelihood, consequence and mitigation options is presented in an interactive web-based tool, GBA Explorer. So looking at the network for the Cooper GBA region, there are 50 nodes, 25 endpoints, they are the values to be protected, and 268 links in the network that make up 2815 pathways from unconventional gas resourse development, from the driver to each of the 25 endpoints. Each link is evaluated using a 500 metre by 500-metre grid that covers the entire 130,000 square kilometre Cooper GBA region. In terms of outputs, there are 876 impact maps, as well as all of the maps for link evaluations and contextual maps that are used to build the causal network. The causal network identifies potential impacts and mitigation options for each pathway and provides a comprehensive baseline for decision-makers.
The assessments are underpinned by a resource development scenario that matches current conventional gas production of 92 petajoules per year from the Cooper Basin. So this is the maximum resource development scenario. We worked out how many wells, well pads, access tracks, and how much water is needed for development. Access tracks and well pads could disturb up to 27 square kilometres which can be spread over 6% of the Cooper GBA region. These impacts could occur in 27% of the Cooper GBA region, just shown by the orange on the map in the bottom right. It's important to note that while these impacts could occur, all potential impacts can be mitigated by existing controls. But that ongoing compliance with regulatory controls, their enforcement and continued monitoring of their effectiveness is critical.
The assessment is supported by detailed investigations to address knowledge gaps. Each investigation is summarised in a two-page fact sheet that gives a high-level overview and links to the datasets, journal papers, or reports for each investigation. There are three groups of investigations. Firstly, is the better understanding of floodwaters, waterholes, and groundwater on the Cooper Creek floodplain. The next group of investigations for the Cooper GBA region use satellite data to test methods for ongoing monitoring and environmental-economic accounts in the remote Cooper GBA region. Finally, protecting aquifers, including the Great-Artesian Basin aquifers was another area of high concern for our investigations.
In conclusion, environmental assessments are complex. We've untangled the connections between what matters in the environment, the development activities that could cause impacts, and where management and monitoring are critical. It's important to remember that this is a regional assessment and it doesn't replace site-specific assessments. Our work provides a comprehensive baseline to help decision-makers from government and industry to better understand where to look more closely and where risks are low-concern when they're assessing development proposals in the future.
All of the datasets, reports, journal papers, and fact sheets produced by the GBA program are now available to the public through the Bioregional Assessment's website, GBA-explorer, and data.gov.au. I want to finish off by acknowledging the contributions from our stakeholders in the region, including traditional owners and members of the regional community, as well as government, industry, other land users, and the technical peer-review group. Thank you.
About the presenter
Dr Kate Holland
Kate is a Principal Research Scientist with over 20 years of experience using multi-disciplinary investigations to support policy makers, industry and regulators. She was the CSIRO project leader for the Geological and Bioregional Assessment Program.
- Bioregional Assessment Program
- Lake Eyre Basin bioregion
- Northern Inland Catchments bioregion
- Clarence-Moreton bioregion
- Northern Sydney Basin bioregion
- Sydney Basin bioregion
- Gippsland Basin bioregion
- Indigenous assets
- Bioregional assessment methodology
- Compiling water-dependent assets
- Assigning receptors to water-dependent assets
- Developing a coal resource development pathway
- Developing the conceptual model of causal pathways
- Surface water modelling
- Groundwater modelling
- Receptor impact modelling
- Propagating uncertainty through models
- Impacts and risks
- Systematic analysis of water-related hazards associated with coal resource development
- Assessment components
- Component 1: Contextual information
- Component 2: Model-data analysis
- Components 3 and 4: Impact and risk analysis
- Component 5: Outcome synthesis
- Metadata and datasets
- Geological and Bioregional Assessment Program