Development of Transient Mechanistic Three-Phase Flow Model for Wellbores

Multiphase flow models have been widely used for downholegauging and production logging analysis in the wellbores. Coexistence of hydrocarbon fluids with water in production wells yields a complex flow system that requires a three-phase flow model for better characterizing the flow and analyzing measured down hole data. In the past few decades, many researchers and commercial developers in the petroleum industry have aggressively expanded development of robust multiphase flow models for the wellbore. However, many of the developed models apply homogeneous flow models with limited assumptions for slippage between gas and liquid bulks or use purely two-fluid models. In this paper, we propose a new three-phase flow model that consists of a two-fluid model between liquid and gas and a drift flux model between water and oil in the liquid phase. With our new method, we improve the simplifying assumptions for modeling oil, water, and gas multiphase flow in wells, which can be advantageous for better downhole flow characterization and phase separations in gravity-dominated systems. Furthermore, we developed semi-implicit and nearly implicit numerical algorithms to solve the system of equations. We discuss the stepwise-development procedures for these methods along with the assumptions in our flow model. We verify our model results against analytical solutions for the water faucet problem and phase redistribution, field data, and a commercial simulator. Our model results show very good agreement with benchmarks in the data.