Title: |
Hot Sedimentary Aquifer Characterization Using Stratigraphic Forward Modelling, Perth Basin, Australia |
Authors: |
CORBEL, S., GRIFFITHS, C., DYT, C. and RICARD, L.P. |
Key Words: |
hot sedimentary aquifers, stratigraphic forward modelling, Perth Basin, Australia |
Geo Location: |
Perth, Australia |
Conference: |
Stanford Geothermal Workshop |
Year: |
2012 |
Session: |
Low Temperature |
Language: |
English |
Paper Number: |
Corbel1 |
File Size: |
424 KB |
View File: |
|
Several geothermal projects in the Perth Metropolitan Area, Western Australia, have already demonstrated the geothermal potential of the area for aquifers down to 2 km. The Western Australian Geothermal Centre of Excellence (WAGCoE ) was tasked with assessing the potential of the deeper aquifers. Members of WAGCoE, in collaboration with CSIRO, investigated the use of stratigraphic forward modeling techniques combined with geothermal reservoir definition to identify potential geothermal reservoirs in locations where data are sparse. The major aquifer and low-temperature geothermal target in the Perth Basin, the Yarragadee Aquifer, provides a major portion of Perth’s drinking water. Although the shallow part of the Yarragadee Aquifer has been well studied by hydrogeologists, the deeper part is still poorly characterized. Stratigraphic forward modelling is a process simulation approach that attempts to replay the deposition of sediments. It enables estimation of the grain size distribution, porosity and permeability based on geological process modelling rather than interpolation between sparse data. Using the stratigraphic forward modelling package Sedsim, the sedimentation of the Yarragadee Formation was simulated over a period of 15.8 Ma, from 160 Ma to 144.2 Ma. The simulation was calibrated against sparse seismic surveys, petroleum wells and core data. The final simulation was uplifted and eroded to the current state of the Yarragadee Formation, providing estimates of facies, grain size distribution, porosity and permeabilities for the entire formation. Once the characterization of the Yarragadee Formation was achieved, the identification of geothermal reservoirs required investigating the suitability of the rocks to deliver the energy required for a given geothermal application. Based on simple assumptions such as thermal conduction, absence of hydrogeological background flow, and using pre-defined geothermal production design settings such as flow rate and maximum pressure drop, parameters such as the reservoir temperature, the local reservoir volume, minimum well spacing and end of production pressure drop are then combined to define geo-bodies forming possible reservoirs for the defined geothermal application. The ability to rapidly re-evaluate the reservoir potential given changes to the geothermal application specifications is a powerful outcome of this approach.
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