Recent national and state assessments have concluded that certain deep geological formations within Australia show considerable suitability for the storage of greenhouse gases. Many of these same formations contain naturally generated methane (CH4) and carbon dioxide (CO2) that have been trapped for millions of years.
An important consideration in assessing the potential economic, environmental, health and safety risks of geological storage projects is to determine the risk and impact that CO2 migrating from a greenhouse gas storage reservoir could have on overlying groundwater resources. While many studies indicate that the risk of CO2 migration out of a storage reservoir is very small, monitoring groundwater quality will be one of many techniques required to demonstrate that CO2 remains within the storage reservoir.
Geoscience Australia is working with the Geological Survey of Queensland to collect regional baseline groundwater information in potential storage basins. The team are also investigating the impact that high levels of naturally occurring CO2 has on groundwater chemistry.
Since 2009, Geoscience Australia and the Geological Survey of Queensland have conducted a total of eight groundwater surveys in the Bowen, Surat and Clarence-Moreton Basins.
The information collected on these surveys includes:
- Field gas analysis for CH4, CO2 and oxygen (O2)
- field pH, electrical conductivity, redox and temperature
- laboratory analysis for alkalinity, total dissolved solids, major cations and anions, trace metals, trace organics, major inorganics, dissolved gas composition, water isotopes and gas isotopes.
A compilation of the survey results from 2009 to 2011 will be made publicly available in 2012.
Baseline Hydrogeochemical Mapping of Aquifers in the Great Artesian Basin
Potential targets for geological storage of CO2 on the Australian mainland include sedimentary sequences that underlie or are within the Triassic-Cretaceous Great Artesian Basin (GAB) aquifer sequence. Geoscience Australia is currently developing regional hydrogeochemical maps of each major aquifer sequence in the GAB. Data collected during joint Geoscience Australia - Geological Survey of Queensland groundwater surveys from 2009 to 2011 have been supplemented with historical hydrogeochemical data compiled from various sources including State, Territory and Federal Government agencies. In addition, hydrogeochemical information was compiled from thousands of petroleum well completion reports in order to obtain more information on the deeper aquifers not typically used for agriculture or human consumption. This data was passed through a quality control procedure to check for mud contamination and whether a representative sample had been collected. The large majority of the samples from petroleum exploration reports contained drilling fluids, but a small selection passed the quality control criteria. The compilation from the well completion reports is available for download.
The point data sources were interpolated and extrapolated using ArcGIS tools to develop hydrogeochemical maps for individual hydrological aquifer units. The hydrogeochemcial maps developed as part of this investigation provide critical information for managing water resources in the GAB. The maps identify locations and aquifers where additional water chemistry data is urgently required, as well as providing a regional baseline of groundwater chemistry. Version 1 of the maps was presented at the Australian National Groundwater Conference in 2010 and an updated Version 2 will be released in 2012.
Topic contact: firstname.lastname@example.org Last updated: September 7, 2012