A Practical Approach to Producing Vapor-Dominated Reservoirs

Abstract

This paper presents arguments for initially producing Geysers steam wells at wellhead pressures in excess of 200 psig instead of the normal practice of producing at minimum wellhead pressures. A conceptual model is presented which defines a flow equilibrium resulting from a "constant pressure source" whose location is a function of the withdrawal rate from the reservoir. Based on this model, it is argued that producing at elevated wellhead pressures is equal to producing at minimum well head pressures, assuming the mass withdrawal is the same. Additional benefits of producing at elevated we1 1 head pressures are discussed and include minimizing casing and reservoir rock thermal transients and scaling and bridging of the wellbore. SFGI's experience has been favorable but due to a very high capacity factor and very few outages, a comparison of performance of other areas of The Geysers is inconclusive.