Geothermal energyProject Geothermal Structural Permeability Map
This project set out to conduct a scientific research-driven analysis of methods for the subsurface detection of structural permeability, the characterisation of these structures, and analysis of their ability to act as conduits for subsurface fluid flow.
This ARENA Measure entitled The Australian Structural Permeability Map Project, set out to conduct a scientific research-driven analysis of methods for the subsurface detection of structural permeability, the characterisation of these structures, and analysis of their ability to act as conduits for subsurface fluid flow.
Structural permeability, or secondary permeability, is defined as pathways for fluid flow through faults, fractures, and other tectonic features. This project arose from a key finding of the now-complete ARENA Measure Reservoir Quality in Sedimentary Geothermal Resources led by South Australian Centre for Geothermal Energy Research (SACGER) was that deep sedimentary aquifers in Australia are unlikely to be viable geothermal reservoirs due to the effect that mineral formation accompanying sedimentary burial has on rock permeability. Consequently, it is likely that structural permeability from natural or induced fracture networks will provide the primary means for fluid flow in geothermal reservoirs.
The outcomes which the project set out to achieve in this ARENA Measure were:
- To map fracture distributions, orientations and their connectivity in key onshore sedimentary basins using a range of geophysical techniques, well-bore image logs, drill core data and outcrop studies.
- To take known fracture populations (see outcome 1) and identify those that are open or closed to fluid flow by investigating fracture histories for a subset of Australian sedimentary basins where key fracture attributes (orientation, aperture) are well understood.
- To define a framework for prediction of permeability pathways within critical Australian basins that is based on our database of fracture character and fracture generation histories.
- To improve our understanding of the relationship between fractures mapped in seismic data and borehole image logs, permeability measurements from both drill core and formation tests, and electrical resistivity including anisotropy.