Physical Performance Tests of a Tandem Ultra-High-Speed High-Gas-Volume-Fraction Pump

Abstract Conventional multiphase pump technologies typically handle intake gas volume fractions (GVFs) of 75%. Recent work has shown development of an Ultra-High-Speed High GVF Pump (UHS HGVFP) with significant boost pressure at 90% intake GVF. The current work discusses the physical performance test results of a tandem UHS HGVFP and showcases pump behavior with increased number of modules. Knowledge from such work is beneficial in multiphase pump sizing for production in high gas-oil ratio wells. A 4 in. housing outer diameter, tandem (double module) UHS HGVFP was tested at a rotational speed of 10,000 rev/min. Air and water were the working fluids, and liquid volume flow rates varied from about 550 to 1980 barrels per day (B/D). The gas flow rates were adjusted accordingly to achieve a 0% to 90% intake GVF range. For each test data, pressures and temperatures at pump intake and pump discharge and gas lines were measured, with corresponding pump boost pressures computed. Pump performance was plotted and results compared with those of a single-module UHS HGVFP at same GVFs. The results showed a steady decrease in boost pressure as the intake GVF varied from 0% (liquid-only tests) to 90%. For the same boost pressures, the magnitudes of liquid volume flow rate delivered by the pump decreased with increasing intake GVF and vice versa. The tandem UHS HGVFP test results were compared to those of a previously tested single-module UHS HGVFP when pumping only water. For the same liquid volume flow rates and intake pressures, the boost pressure from the tandem-module was, on average, about two (2) times those of the single-module UHS HGVFP. This indicates that for liquid only tests, doubling the number of stages also doubles the pump boost pressure. For intake GVFs from 15% to 90%, the tandem UHS HGVFP produced about 1.24 to 1.88 times the boost pressure of a single-module UHS HGVFP. Lower boost pressure ratios were observed as intake GVF approached 90%. These results indicate that at higher intake GVFs, doubling the number of modules does not double the boost pressure boost capability of the pump. Knowledge gained from these tests are vital for successful multiphase performance sizing of the UHS HGVFP ahead of field installation and trial. At low intake GVFs, a tandem (2-module) UHS HGVFP can produce double the pressure boost of a single-module UHS HGVFP, but is not the case at higher intake GVFs up to 90%. Knowledge of such performance trends are crucial for proper sizing of the UHS HGVFP. Results from this study indicate that a series of multiple-module UHS HGVFP has superior capabilities to handle multiphase flows in wells with high gas-oil-ratios.