Scale Inhibitor Test at the Hijiori HDR Site, Yamagata, Japan
- Key words
- Geofluids; scale inhibitor, sodium polyacrylate, calcite, anhydrite, HDR, hot dry rock, EGS, enhanced geothermal system
- Conference
- Geothermal Resources Council Transactions
- Year
- 2006
- Session
- Geofluids; Scaling; sodium polyacrylate; calcite; anhydrite;
- Language
- English
Abstract
During circulation test of HDR system at Hijiori, anhydrite precipitated at a deep area of the production well and caused problems for survey and production. As a countermeasure to this problem, we tried to use scale inhibitor, sodium polyacrylate, C2H3COONa and injected it into the reservoir in this system. After inhibitor was injected, production fluid chemistry changed. HCO3 concentration increased with inhibitor suggesting that the inhibitor can be used prevents precipitation of calcite in many geothermal fields. However, SO4 concentration decreased with inhibitor suggesting that the effect of inhibitor to anhydrite is different than calcite. After we checked the solubility of anhydrite with inhibitor, it becomes clear that this inhibitor prevent to solve anhydrite at lower temperature. This suggests that this inhibitor effect for anhydrite and for scale prevention in HDR system.
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