Hot dry rock research experiments at Fjallbacka, Sweden

A number of in-situ experiments, aimed at investigating geological, hydroge ological and hydromechanical aspects of HDR reservoir development were carr ied out at the Fjallbacka test site in western Sweden between 1984 and 1995 . By means of hydraulic stimulations, a roughly horizontal reservoir that c onnects two 500 m deep wells was created. An open-loop circulation test per formed between the wells gave a flow recovery of about 50%. All major fluid injections have resulted in microseismic activity due to shear failures. A cross-hole seismic survey of the inflated reservoir provided some addition al evidence of the distribution of hydraulically active fractures. (C) 1999 CNR. Published by Elsevier Science Ltd. All rights reserved.