A generalized model for predicting the performance of gas reservoirs subject to water drive

Abstract

A calculation procedure for predicting the performance of water-drive gas reservoirs without the usual assumptions of simplified geometry and homogeneity is presented. A characteristic pressure drop curve for a constant rate of water influx is calculated from field-performance data. Its extrapolation allows prediction of future water movement and pressure behavior when a projected production or pressure schedule is given. The procedure has been extended to handle "moving boundary" problems resulting from the growth of the gas bubble in early stages of aquifer storage. Two field case histories are presented where predicted performance is compared with direct field data.