Geysers Reservoir Performance

Abstract

Exploitation of the Geysers began about 140 years ago with the construction of a resort hotel. Electric generation commenced in the 1920s upon the completion of several shallow steam wells. A steam engine driven generator supplied roughly a kilowatt to electrify the resort through the 1930s. The current large scale development began with drilling in 1955 and the first 12 MW plant in 1960. Additions in the 1960s brought field capacity to 78 MW. The first phase of sustained development started in 1971, with an average of 67 MW/year installed through 1981. Growth accelerated to 150 MW/year in the second phase (1982-89). The second phase of expansion has been accompanied by 100-200% increase in reservoir decline rates. Steam deliverability field wide has peaked, and substantial declines have been experienced. The reservoir response indicates the field is fully developed. Performance forecasts have been made using both numerical models and direct t extrapolations of pressure and flow rate trends. Both methods suggest that field life will exceed to years. However, Unocal production will probably decline from 16 million be/hr to 6 million lb/hr in the next 10 years.