Thermal Drawdown Analysis of the Hijiori HDR 90-Day Circulation Test

Abstract

The Hijiori 90-day circulation test is unique in the development of HDR technology in that it was the first (and thus far the only) multiproduction well test run for a sufficient production period to obtain observed cooldown curves at multiple production horizons in the stimulated reservoir volume. The experimental data have been analyzed by the SGP 1-D linear heat sweep model to examine the extent of thermal cooldown in this relatively small, multi-well, multi-zone reservoir. Although changes in production flow were carried out in specific wells at specific times during the 90 days of circulation, matching of the observed cooldown curves in conjunction with the structural and temperature logging data allows estimation of the reservoir volume and the mean fracture spacing between rock blocks for heat extraction during the 90-day test.