Determination of Original Oil in Place by the Material Balance Method for A Reservoir with Initial Gas Cap and No Water Influx

Abstract

The program performs a set of material balance calculations at different time steps for a reservoir with an initial gas cap. In the formulation of the material balance equation, it is assumed that the reservoir produces under a combined (solution gas and gas cap) expansion drive. Gravity effects and water influx are assumed negligible. The water and rock compressibilities are also neglected. For the purpose of material balance calculations, the gas-cap gas volume as well as the oil-band oil volume must be known. These volumes usually are computed using the volumetric method. The original oil-in-place determination by the material balance procedure is often considered a secondary check.