Electrical submersible pumps (ESPs) must handle two-phase flow (liquid and gas) conditions in production wells. Pump stages are designed for liquid handling, and the pump performance is significantly affected by the presence of gas. ESPs are tested in two-phase flow conditions, and performance is measured stage by stage to improve the understanding of gas, its limitations, and its effects.
ESPs are tested in a high-pressure, two-phase flow loop. Pumps are instrumented across stages for pressure measurements. Pumps are tested at intake pressures between 50 and 250 psi, with gas percentages of 0 to 95% maximum, and at different flow rates ranging from 40 to 70 Hz for complete performance mapping. The flow loop is capable of up to 80+% gas and 250 psi intake pressure at the pump intake, running up to 60 Hz, 300 HP, and 18,000 bpd of fluid. Pump performance is evaluated for the various gas conditions at various speeds and intake pressures.
Pump performance is significantly affected in two-phase applications. The performance deteriorates with an increase in the gas percentage and improves with an increase in the speed and the intake pressure. Mixed flow pumps handle gas better than radial flow pumps. Larger diameter pumps have higher gas handling capabilities than smaller diameter pumps.
Sizing taper pumps operating in a flow range higher than the BEP flow range and additional pump stages in the sizing provides longer life, higher reliability, and more efficient operation in gassy applications. Pump performance under various downhole conditions was investigated, and a new technique was developed for the sizing of ESPs in two-phase flow applications.