Application of Magnetic Method to Assess the Extent of High Temperature Geothermal Reservoirs
- Key words
- Geophysical Exploration, Airborne and Ground Magnetic Surveys, Volcanic Reservoir Rocks, Hydrothermal Demagnetization, Near Surface Alteration, High Temperature Reservoirs.
- Location
- Taupo Volcanic Zone; Wairakei, New Zealand; Te Kopia, New Zealand; Tokaanu, New Zealand; Waihi, New Zealand; Kawah Kamojang, Indonesia; Java
- Conference
- Stanford Geothermal Workshop
- Year
- 1995
- Session
- Geoscience
- Language
- English
Full text
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Abstract
The extent of thermally altered rocks in high temperature geothermal reservoirs hosted by young volcanic rocks can be assessed from magnetic surveys. Magnetic anomalies associated with many geothermal field in New Zealand and Indonesia can be interpreted in terms of thick (up to 1 km) demagnetized reservoir rocks. Demagnetization of these rocks has been confirmed by core studies and is caused by hydrothermal alteration produced from fluidhock interactions. Models of the demagnetized Wairakei (NZ) and Kamojang (Indonesia) reservoirs are presented which include the productive areas. Magnetic surveys give fast and economical investigations of high temperature prospects if measurements are made from the air. The magnetic interpretation models can provide important constraints for reservoir models. Magnetic ground surveys can also be used to assess the extent of concealed near surface alteration which can be used in site selection of engineering structures.
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