A Numerical Model for Multiphase Flow on Oil Production Wells

Abstract A numerical model for the analysis of multiphase flow on vertical or slightly inclined wells has been developed. The model calculates flow properties (velocity of each phase, volumetric fraction of each phase, pressure and fluids properties) on gas-oil-water wells as function of depth. Fluids properties are obtained under the assumption of black oil model by means of correlations taken from literature, requiring only petroleum °API and the gas specific gravity as input data. The model may be applied to simulate both liquid flow and gas-liquid flow. In this case, different flow patterns are taken into account: -bubble, slug, dispersed bubble and annular-depending on flow conditions, which are determined from fluid properties and production rates of oil, gas and water. Flow in tubings consisting of several sections with different diameters and inclinations may also be simulated. The model was validated by comparisons of measured and calculated the pressure variation along the well Good agreement was found between the numerically predicted pressure drop and measurements taken from different databases from open literature. As a consequence the proposed model proves to be a reliable tool to describe the flow on oil-gas-water wells. The developed numerical model takes into account the most relevant effects that take place in a production well including multiphase flow, presence of different flow pattern, mass transfer from gaseous to liquid phase and influence of gas-liquid flow pattern on wall friction. Special attention is paid to the velocity profile of each phase along the well. Ishii's model for two-fluid flow is used to prescribe the slip velocity between liquid and gaseous phases and to determine the acceleration term contribution to the pressure gradient. This model is actually being employed for corrosion rate calculations inside production wells.