The dependence of permeability on effective stress from flow tests at hot dry rock reservoirs at Rosemanowes (Cornwall) and Fenton Hill (New Mexico)

E€ective stress is the primary control on permeability and thus on ¯ow and water loss for two-well hot dry rock systems involving injection and production that have been tested to date. Theoretical relations are derived for the ¯ow between an injector and producer, including the dependence of permeability on e€ective stress. Four relations for permeability as a function of e€ective stress are used to match ®eld data for the hot dry rock systems at Rosemanowes, Cornwall, and Fenton Hill, New Mexico. The ¯ow and water loss behavior of these systems are well explained by the in¯uence of e€ective stress on permeability. All four relations for permeability as a function of e€ective stress are successful in matching the ®eld data, but some have diculty in determining unique values for elastic and hydrologic parameters. # 1999 CNR. Published by Elsevier Science Ltd. All rights reserved.