Expanding Resource Development of the Southeast Geysers Steam Field

Abstract

In 1974 Shell Oil bid $4.5 million for two federal leases (4077 ac.) located south of production at The Geysers. Shell's second well discovered dry steam, triggering five stages of expanding resource development. Initial development of 69MW of steam prompted a 110 MW power plant commitment from NCPA in 1978. Stage Two saw completed development drilling for Plant #1, a 55 MW Plant #2 commitment, ending with Grace Geothermal buying the steamfield in Sept 1983. Limited drilling by Grace constituted Stage Three. NCPA consequently purchased the steam field in 1985, undertaking the accelerated development drilling required to supply impending startup of Plant #2 (meantime doubled to 110 MW capacity). The Stage Five objective is to now maintain 265 MW of available steam. To combat depletion the steam field area was recently expanded by 76%, and augmented injection is planned for improved reservoir pressure retention.