Performance Envelope of a High-Speed High-GVF Helico-Axial Pump

Abstract

AbstractOperating a pump at high speeds can have the benefit of increasing the capability of pumps to enhance surface or downhole production of fluids with high gas volume fraction (GVF). This study presents the performance envelope of a high-speed helico-axial pump (HAP) operating at high GVFs (> 80%). The ultimate aim of the physical tests was to ascertain the operating capabilities of the pump for potential scale-up to a field prototype.The HAP housing outer diameter was 5.38-inch and operated at a rotational speed of 6000 revolutions per minute (RPM). Air and water were the test fluids, with average pump intake temperature of 25°C. The fluid volume flow rates were varied to maintain 50 psig at the HAP intake. The liquid and total intake volume flow rates varied from 128 to 664 barrels per day (BPD), and 4941 to 7593 BPD, respectively. The corresponding discharge pressures and temperatures, as well as electrical power input and current draw to the HAP motor, were also recorded.The results showed that the HAP had stable operation during the tests for intake GVF range from 91% to 98%. The corresponding pump discharge pressures were in the range of 58 to 101 psig. This indicated the capability of the HAP to boost fluid pressure even for such high intake gas content. The results also showed that HAP boost pressure was positively correlated with liquid volume flow rates, and negatively correlated with the intake gas volume flow rates. Overall, the boost pressure decreased with intake GVF. The electrical input power to the HAP motor varied between 16 to 37 kW. It was observed to strongly increase with increasing liquid volume flow rate, and very strongly decrease with increasing HAP intake GVF. The associated electrical current draw by the HAP motor was seen to vary between 31 and 68 A. Its variation with liquid volume flow rate and intake GVF was similar to those of the electrical power input. In conclusion, the HAP demonstrated capability to boost fluid pressure when handling high GVF flows. It is being scaled up to a field prototype to handle higher volume flow rates of high GVF gas-liquid mixtures.This study mainly highlights the method to extend the gas-handling capability of a HAP by operating it at high speeds. Optimal hydraulic design and proper conditioning of the inlet flow components were also incorporated in the HAP architecture. Expanding the HAP operating envelope to handle high-GVF flows significantly unlocks the potential for field operators to maximize hydrocarbon production from high-gas content applications. This, in turn, increases the economic bottom-line from the field asset.