Operating experience with the experimental HDR system at the Camborne School of Mines [geothermal power]

Summary form only given. A large viscous stimulation of the granite in Cornwall was carried out, creating a HDR (hot dry rock) reservoir which has subsequently been circulated continuously since August 1985. During this period the reservoir has been operated under several different flow and pressure regimes in a series of experiments designed to discover the hydraulic operating limits of the reservoir that had been created. This work has been successfully completed with the discovery that the upper operating pressure and hence flow rate is limited by the effective in-situ earth stresses. As a result significant further improvement in the operating characteristics of the reservoir are probably only achievable by additional stimulation work. In addition to investigating the hydraulic operating limits of the reservoir its thermal behaviour has been monitored and an investigation, using tracers, of its flow paths has also been carried out