1998 Fiscal Year Final Research Report Summary
Reduced factor of permeability in a geothermal reservoir
| Project/Area Number |
09651032
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
資源開発工学
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| Research Institution | Science University of Tokyo |
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Principal Investigator |
MURAMATSU Yoichi Science University of Tokyo, Faculty of Science and Technology, Associate Professor, 理工学部, 助教授 (70266922)
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| Project Period (FY) |
1997 – 1998
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| Keywords | permeability / self-sealing / fluid inclusion / anhydrite / prehnite / microthermometry / cathodoluminescence / fluid-mineal equilibria |
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| Research Abstract |
Productivity of a production well at geothermal fields depends on a permeability of a opened fracture where is a path of present geothermal fluid. The purpose of the project is to clarify a possibility of reduce of the fracture permeability by progress of self-sealing due to precipitation of hydrothermal minerals from the present geothermal fluid. The definite studies for Kakkonda geothermal field, Iwate prefecture, are as follows : (1) mineralogical and microthermometric studies of rock materials ejected from a production well (2) microthermometric and sulfur isotopic studies of anhydrite which is a representative hydrothermal mineral in the upflow zone of the field (3) calculation of geothermal fluid - hydrothermal mineral equilibria (4) observation of anhydrite by the use of cathodoluminescence. From these research, it is concluded that the opened fracture is presently sealing by precipitation of prehnite and so on. Moreover, a preliminary examination shows that the cathodeluminescence is a very useful method to determine a specified anhydrite which was precipitated from the recent geothermal fluid of several anhydrite formation stage.
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