A Robust Density-Based Approach to Production Data Analysis of Oil/Water Multiphase Flow System

Abstract

This paper presents a novel approach to estimate reserves of oil and water reservoirs undergoing boundary-dominated flow conditions in a simplified yet accurate manner. The methodology incorporates rescaled density-based exponential models and is based on the coupling of two-phase oil and water material balances with multiphase well deliverability equations. Current multiphase production data analysis methods employed for reserve calculations, including density-based approach, are subjected to the determination of saturation–pressure relationship, multiphase pseudo-pressure, and pseudo-time, as well as the iterative nature of its own algorithm. The herein proposed approach circumvents the need for pseudo-variables calculations, thus precluding the determination of saturation–pressure relationship and removing the iterative nature often present in state-of-the-art approaches. The proposed model is validated by comparing its predictions to numerical models with both constant and variable bottomhole pressure constrains, and has been found to match closely. For all cases, relative errors are found to be less than 1%.