Measurement of high water-cut heavy oil flow based on differential pressure of swirling flow

Abstract

Real-time measurement of heavy oil production is critical to ensure stable production. Due to the complex kinematic characteristics of heavy oil, existing methods cannot accurately measure its flow rate and water cut. In this paper, a novel method is proposed to measure the high water-cut heavy oil flow by using the differential pressure of the two-phase swirling flow in the pipe. For the swirling flow in the pipe, the radial differential pressure and the axial differential pressure exist simultaneously, which are very sensitive to the flow rate and water cut. The formation mechanism of the two kinds of differential pressure is analyzed theoretically, and their relationship with flow rate and water cut is studied by experiment and numerical simulation. The measurement model of heavy oil–water two-phase flow on the above relations is validated by field experiments. The radial differential pressure is only related to the two-phase flow rate, varying exponentially with the flow rate when the oil viscosity is greater than 10 000 mPa s. This characteristic is very useful for the heavy oil–water two-phase flow measurement. The axial differential pressure decreases with the increase in water cut in cases of water cut <85%, while it increases with the water cut in cases of water cut >85%. With the increase in water cut, the ratio of axial differential pressure to radial differential pressure first decreases and then increases. The relative errors of the established measurement model for flow rate and water cut are 0.19%–17.92% and 0.21%–15.5%, respectively, and more than 70% of the measurements with a relative error of less than 10%. The study of the heavy oil–water two-phase flow measurement method can optimize the measurement cost and accelerate the process of intelligent oilfield construction.