抄録
The Yamagawa gethermal power plant started on the 30 MW commercial operation in March 1995. Since December 1997, steam production has been falling down to about 60% of full scale production by some serious troubles of production wells and injection wells. Major problems of production wells are precipitation of sulfide scale inside the well and decline of discharge enthalpy, and major problem of injection wells is decline of injection capacity because of precipitation of silica scale. It seems that those problems are origenated from the characteristics of Yamagawa geothermal reservoir, those are high reservoir temperature, high sanility, high discharge enthalpy from the well and existence of cool zone at the depth of 1, 000 m. Present status of the Yamagawa power station is making up the programfor solving the serious problems by drilling new wells for recovering the generation power.
