Experimental Study of Two-Phase Air-Water Flow Behavior at Different Intake Flow Conditions of an Electric Submersible Pump

Electric Submersible Pumps (ESP) are efficient artificial lift equipment utilized in oil and gas industries to enhance hydrocarbon or water production from wells by lifting high volumes of low-pressure fluids from the well-bores up to surface. The presence of free gas at the pump-intake is a big challenge to achieve the maximum potential from oil wells. To improve ESP performance, it is necessary to understand the two-phase flow behavior at the ESP intake. The objective of this work is to study the two-phase air-water flow behavior at the intake of an ESP for different operating conditions. In this study, a set of experiments were conducted using a two-phase prototype test flow loop. The total fluid mixture flow rate was 1250 barrels/day (bpd), inlet pressure was approximately 1.5 barg $(\sim 22$ psig) and inclination angles to the horizontal were 45° and 90°. The intake gas volume fraction (GVF) was varied from 10% to 70%. For this preliminary study, the ESP rotational speed was kept at zero RPM. Images of the air-water flow conditions in the plexiglass test section upstream of the ESP were captured using a high-speed camera. At lower intake GVFs (10 & 30%), dispersed bubbly and occasional slug flow patterns were observed. At higher intake GVFs (50 & 70%), larger slugs and liquid flow reversal (liquid bubbles falling back) were observed. It was also observed that the density of bubbles increased with increasing intake GVF. Observations from this study will be helpful to mitigate challenges associated with ESPs producing high gas content two-phase flows, which are common in oil and gas industries. Furthermore, understanding factors influencing ESP gas-liquid behavior at intake and incorporating suitable components into the ESP assembly will prevent operational problems such as surging and gas locking. The end goal is reduction of ESP downtime, as well as significant decrease in field operation and production cost.