A Study of Pressure Gradient Characteristics of Oil-Water Dispersed Flow in Horizontal Pipe

Abstract

The behavior of oil/water dispersed flow is one of the oil/water two phase flow phenomena encountered in pipeline operations commonly. Due to the different operation conditions, kinds of flow patterns (O/W and W/O) can be observed, as well as the phase inversion point. Pressure gradient characteristics of the three flows vary greatly. Pressure gradients at phase inversion point are higher than those under other conditions which pose great harm to pipeline operations. Three oil samples of different viscosities were used in this study. Mixture flowrate, oil content and mixture temperature data were obtained for oil-water tests. Data analysis shows that pressure gradients exist 3 different stages as oil content changed (O/W stage, phase inversion stage and W/O stage). Pressure gradient characteristics behave differently during the 3 stages. The viscosity of the continuous phase is the dominant factor affecting pressure gradients and droplet size and number also play a role. High mixture velocity will promote pressure gradients. Mixture velocity also affects the viscosity of the working fluid. High velocity lowers apparent viscosity and decreases pressure gradients. The increment rate of pressure gradients can slow down with the increase of mixture velocity. Mixture temperature mainly affects the viscosity of the continuous phase and creats tiny effect on the dispersed phase. High temperature lowers the viscosity of the continuous phase and decreases the pressure gradients.