Some Considerations on Resource Evaluation of The Geysers

Abstract

Although large amounts of data have been collected at The Geysers, some reservoir parameters, such as initial liquid saturation, matrix permeability and the fracture network characteristics, are still poorly known. These parameters greatly affect results of resource evaluation and predictions of reservoir behavior. Several two dimensional fractured porous medium models have been developed for the Geysers; these models differ in assumptions regarding the initial saturation and matrix permabilities. These models indicate that the permeability thickness product (kH) of the fracture network ranges from 10 to 75 Dm (30,000 to 225,000 md:ft) and matrix permeability ranges from 1 to 3 Darcies. All three models yielded surprisingly similar predictions regarding the future generating capacities of different areas.