Thermal Consolidation in a Vapor-Dominated Reservoir

Abstract

Thermal consolidation due to vapor production from a vapor-dominated geothermal reservoir with natural recharge from an overlying liquid layer is examined. When the vapor is extracted, the pressure declines and the liquid vaporizes as the liquid layer descends into the vapor zone. It is shown that the flow-induced pressure change is comparable to the hydrostatic profile for a typical production rate and that the subsidence is mainly from thermal compaction in the liquidinvaded zone. The total subsidence in the reservoir increases as the production rate increases but decreases as porosity decreases. The permeability variation only affects the reservoir life in such a manner that the processes are inversely proportional to the permeability change.