| Title | Nationwide Geothermal Assessment in Japan by a Volumetric Method |
|---|---|
| Authors | Y. Miyazaki, H. Tsu, M. Urai, S. Takakura, Y. Okubo and K. Ogawa |
| Year | 1990 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | |
| Abstract | Geothermal resource assessment is the estimation of the amount of thermal energy that might be used economically at some reasonable future time. This resource assessment is of importance for providing a framework for long-term energy policy and strategy decisions by government. Total Japanese geothermal resources of hydrothermal convection systems were assessed by a volume method in nation-wide scale. These systems were classified into three categories, High-temperature hydrothermal convection Intermediate-temperature Low-temperature The resource calculation was performed with SIGMA (System for Interactive Geothermal Mapping and Assessment) computer systems at Geological Survey of Japan which is an integrated information system on geothermal resources. Data used for this assessment are nation-wide Bouguer gravity anomaly data and Curie isothermal depth data collected by NEDO (New Energy and Industrial Technology Development Organization), topographic data, and well-logging data which are archived on SIGMA system. The methodology used in determining the accessible geothermal resource base for each hydrothermal convection system is essentially the same as a typical volume method presented in the paper of Brook et but which is slightly modified. Reservoir temperature is estimated by Curie isothermal depth data, and subsurface areas and thicknesses of reservoirs are estimated by gravity basement depth data assuming geothermal reservoirs are limited by impermeable basement rocks. Thermal energy recoverable at the surface from high -temperature convection systems is estimated to be J. This could contribute 20,540 megawatts of electricity for 30 years. |