| Title | The Deeper Parts of the Geysers Thermal System- Implications for Heat Recovery |
|---|---|
| Authors | Dennis Nielson and Joseph Moore |
| Year | 2000 |
| Conference | World Geothermal Congress |
| Keywords | brittle-ductile |
| Abstract | High temperature hydrothermal convection systems are driven by the energy from shallow igneous bodies. The transfer of heat to the hydrothermal convection zone takes place across a zone of heat conduction from the intrusive to the overlying fluid circulation system. The transition from the convective to conductive thermal regimes is an important interface whose character and location changes with the evolution of the system. In some cases, this boundary appears to be related to the transition form brittle to ductile mechanical behavior. In other cases the boundary lies above the brittle ductile boundary and results from situations where the rocks are under compressive stresses or where the lithology is not able to sustain fracture permeability. Evidence also suggests an important physical boundary may be present at temperatures of about 340oC, below the temperature of the brittle ductile transition. We believe it may be possible to mine heat from areas below the hydrothermal convective zone through deep injection. |