Application of Pressure Transient Analysis to Gas Material Balance for Multi Rate Production

Abstract A producing field's oil and gas reserves are continually estimated throughout its lifetime. As more data about the reservoir is obtained over time, the uncertainty regarding the actual amount of reserves decreases. Various methods have been employed to determine these reserves, including the Material Balance Technique. The classical method applies the conservation of mass, which has evolved over time. This study aims to further enhance the gas Material Balance Technique by incorporating equations derived from analytical pressure transient analysis with multiple rate production. By combining transient analysis solutions with the linear Material Balance method, this approach offers the advantage of determining the initial gas-in-place, permeability, and skin of a reservoir simultaneously, without relying on independent sources for prior knowledge of any of these parameters. To streamline the process and facilitate analytical deductions, this work also utilizes Python programming for automation. Ultimately, this study develops a series of steps that were applied to a case study, enabling the simultaneous determination of the reservoir's permeability, skin-factor, and initial gas-in-place.