Water-Rock Interactions During a Three Month Circulation Test at the Hot Dry Rock Test Site in Hijiori, Japan

Abstract

A three month circulation test was conducted in 1991 at the Hijiori hot dry rock test site. We conducted six tracer tests during the circulation test. The injected water into a well SKG-2 and the produced fluid from three production wells, HDR-1, HDR-2, and HDR-3, were collected during the tracer tests. Major dissolved species were analyzed beside tracer reagents such a I, Br, and fluorescein. Chemistry analysis was used to evaluate rock water interactions in the fractured reservoir. Although the distance between the injection well and the three production wells are less than 60 m and the breakthrough time in each flow path is less than 7 hours, concentrations of dissolved species increased in produced fluid. Difference of produced fluid chemistry is mainly caused by the difference of the reservoir temperature.