Determination of pore compressibility and geological reserves using a new form of the flowing material balance method
Abstract Pore compressibility is an important parameter in reservoir engineering. However, its variation from laboratory core analysis or logging data can be large. Moreover, laboratory core analysis cannot identify the influence of macroscopic fractures on pore compressibility. The geological reserves obtained with the commonly used flowing material balance (FMB) method are significantly impacted by the accuracy of the pore compressibility. Therefore, a new form of the FMB method is proposed in this study which can determine the pore compressibility and geological reserves at the same time. For gas wells, the new method uses the material balance equation and the FMB equation including the pore compressibility. For oil wells, new forms of the material balance equation and the FMB equation were established which have the same form as the corresponding equations for gas wells. A new linear expression of the material balance equation is employed for the analysis. Simulation results indicate that the new method can provide more precise predictions of both the pore compressibility and the geological reserves. Furthermore, the new method also considers the influence of formation fractures because it uses well production data. Sensitivity analysis indicates that the error in the pore compressibility has a significant influence on the determination of the geological reserves.