AN EXPERIMENTAL STUDY OF SURFACTANT EFFECT ON GAS TOLERANCE IN ELECTRICAL SUBMERSIBLE PUMP (ESP)

An experimental study on ESP boosting pressure under air water flow with/without surfactant injection is presented. The experimental facility comprises of a 3-inch-diameter stainless steel liquid loop and 1/2-inch-diameter gas loop. A radial-type ESP with 14 stages assembled in series was installed in the testing bench. Pressure ports were drilled at inter-stage to measure the stage-by-stage boosting pressure. Surfactants, isopropanol (IPA) were injected to change interfacial properties of working fluids. Experiments were carried out with mapping and surging test schemes to evaluate pump behaviors at different operational conditions. ESP pressure increment under single-phase water flow agrees well with manufacture curves. For mapping tests without surfactant injection, ESP performance suffers from a severe degradation as gas flow rate increases. High gas entrainment rate causes oscillations of liquid flow rate and pump boosting pressure. A sudden drop of ESP pressure increment, termed as pressure surging, occurs at the critical inlet gas volumetric fraction (GVF). At higher rotational speeds, the critical GVF is higher. With surfactant injection, ESP boosting pressure improves significantly. With different GVFs, only mild degradation was observed. Pressure surging phenomenon disappeared. Further, liquid flow rate and pump boosting pressure are more stable at high GVFs compared to experimental data without surfactant injection.