| Title | Heat Extraction Using a Downhole Coaxial Heat Exchanger -Preliminary Considerations for Power Generation Using a Downhole Coaxial Heat Exchanger System (I) |
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| Authors | Morita, K., and Sugimoto, S. |
| Year | 1988 |
| Conference | Japan International Geothermal Symposium |
| Keywords | |
| Abstract | A downhole coaxial heat exchanger (DeHE) is applicable to a wide variety of geothermal resources. Especially it is suitable for the development of super hot formations, magma bodies and low productive geothermal reservoirs which produce insufficient amount of hot water or steam for power generation or direct use. These resources were regarded as difficult to develop by ordinary technologies. However, previously proposed DCHEs were not efficient in heat extraction performance, and thought to be not practical method. The authors investigated the effect of design parameters and operational parameters on the performance of the DeHE using numerical simulator, and clarified that the reverse circulation with highly insulated inner pipe increases thermal output of the DCHE significantly (Morita et al.,1985; Morita and Matsubayashi,1986). A series of studies (Sugimoto and Morita,1988; Yamada et a1.,1988; Fujita et a1.,1988) were carried out on power generation using the DeHE for the specified well design and temperature distribution in the formation. The purpose of these studies are to clarify at what thermal output or effective thermal conductivity of the formation the system becomes economical. In these studies, four effective thermal conductivities of the formation were assumed, and power generation costs were estimated for the four cases. The computed results such as thermal output and injection pressure were described in this paper. The capacities of the power plants and electric net power outputs were estimated in the separate paper(Sugimoto and Morita,I988) based on these results. |