Scales from Fluid of Granite Reservoir in Geothermal System

In Hijiori HDR test site, a long‐term circulation was conducted from November 2000 to August 2002. During circulation test, we carried out tracer test and collected scale samples at pipeline and deep production well. The power generation test was carried out last 3 month after 1 month preparation for power plant and pipeline and separator were cleaned up before test. During power generation test, breakthrough and peak volume were gradually decreased and anhydrite scale was picked up from 2000 meter depth of well by PTS survey tool. After power generation test, we measured the thickness of calcite scale on pipeline of HDR‐2. About 40 to 60 mm thickness means about 2.7 ton calcite precipitations. And we estimated the calcite volume from fluid chemistry using Ca, HCO3 and SO4 composition. As Ca is 40/96 of SO4 before calcite precipitation, about 12 ton calcite precipitations on pipeline and shallow part of production well.