| Title | Australia's Favourable Geological Environment for Economic Extraction of HDR Energy and Current Proposals |
|---|---|
| Authors | Doone Wyborn and Prame Chopra |
| Year | 1997 |
| Conference | Japan International Geothermal Symposium |
| Keywords | |
| Abstract | Geothennal energy has, until recently, not been regarded as a major future source of energy for Australia. However the coupling of knowledge learned from US. European and Japanese hot dry rock (HDR) programs with an understanding of the temperature and stress regimes pertaining to the Australian continental crust has dramatically changed that view. The economics of extracting large amounts of HDR energy from a large rock volume with a minimum number of drill holes of minimum depth is suggested to be highly attractive in Australia because of the unique combination of a number of independent geological conditions. These are: 1. In much of central and eastern Australia the crustal heat generating capacity is twice that of nonnal continental crust. 2. Much of the Australian continent is covered by sedimentary basins which contain a high proportion of coal measures and shales that have low thennal conductivities. thus providing an insulating blanket for the heat being generated beneath. 3. The sedimentary basins are in many places underlain by large untectonised granite bodies that are a major contributor to crustal heat generation. Such granite bodies are likely to be ideally suited to the establishment of HDR reservoirs because of their homogeneous character and intricately distributed joint sets. 4. The crustal shortening stress field that is found in the majority of the Australian continental crust results in a vertical minimum principal stress orientation which should result in horizontal propagation during fracture stimulation. As a result of the new understanding plans are being put into place to attempt to exploit these energy resources. A study of the rock properties and stress conditions in the Cooper Basin area of South Australia has begun, and will lead into a microfracture stimulation program in a gas exploration well to detennine the extent and direction of fracture propagation. The project is funded by the Australian Government through the Energy Research and Development Corporation, and by a number of industry partners. In the northern part of the Sydney Basin a geothennal anomaly discovered by the local electricity utility during a search for coal-bed methane is the focus of attention. A company with part ownership by major Australian resource and mining companies has been established to carry out a pilot two-well circulation program. |