Numerical modeling of the critical pipeline inclination for the elimination of the water accumulation on the pipe floor in oil-water fluid flow

Abstract

In this work, numerical models were developed to investigate the critical inclination of a pipeline to eliminate the water accumulation at the floor of the pipe carrying oil-water fluid. Computational fluid dynamics software was used to establish a geometric model of the pipe with various inclination angles, and a grid-independent verification was conducted to determine a reasonable meshing method. Quantitative relationships were determined between the pipe inclination angle and the affecting factors including the flow velocity, viscosity and the pipe diameter, where the water accumulation would not be able to occur. Generally, the critical inclination angle increases with the fluid flow velocity. The refluxing of water is the key mechanism causing the water accumulation at the bottom of the pipe. In addition to the fluid flow velocity, an increase in fluid viscosity and a decrease in the pipe diameter cause an increase of the critical inclination angle that the water phase can be carried away by oil. The model can be used to determine the critical inclination of pipelines carrying oil-water fluid to cause the water accumulation and the operating conditions that can eliminate the accumulation of water phase at the pipe floor.