Experimental and Simulation Studies on the Slug Flow in Curve Pipes.

Abstract

This work focuses on the two-phase slug flow in the curve pipe, which is very common in oil/gas wells. In terms of oil and gas production, the unstable slug flow may cause several problems and reduce production. In the present work, slug flow experiments were conducted in several curve pipes for varying inflow angles and gas–liquid velocity ratios. The real-time pressure was measured at the curve pipe using the Rosemount pressure gauges, and the liquid holdup was measured using the conductivity sensors, which were used to calculate the slug length. Then, we define the dimensionless slug length φD = LS/D (the ratio of slug length L to pipe diameter D), which can make the slug analysis free from the influence of different pipe diameters; φD is also used to analyze the change in the slug flow state. The experimental results show that the dimensionless slug length φD increases with the increase in the pipe curvature; φD first decreases and then increases with the increase in the inflow angle; φD also increases with the increase in the gas–liquid velocity ratio. This study adopts a dynamic slug flow model to simulate the well completion and the throttle cases under field conditions based on the hydraulic similarity principle. The pressure and liquid holdup results show that the large-scale segregated completion will lead to decreasing flow instability and the decrease in throttle opening will also lead to the decrease in flow instability.