A New Decline Curve Analysis Method Applied to The Geysers

Abstract

A decline curve analysis model was developed based on the theory of fluid flow mechanisms with relative permeability and capillary pressure included. The model reveals a linear relationship between the production rate and the reciprocal of the cumulative production. The model was applied to the production data of 61 production wells in The Geysers geothermal field and a linear relationship was found between the production rate and the reciprocal of the accumulative production for the wells, especially at the late period of production. Comparison with common methods to estimate reservoir reserves indicates that the new method gives a more definite estimate of reservoir behavior. The method can also calculate two constants obtained from the linear relationship that have physical significance and can be used to characterize the regional geological properties of the reservoir.