Physical Testing of a High-Speed Helico-Axial Pump for High-GVF Operation

Abstract

Abstract High-speed rotordynamic pump operation for downhole or surface production is required and also beneficial to handle very high gas volume fraction (GVF) flows. Operating speeds of these pumps can be in excess of twice those of conventional pumps. This study presents results of a high-speed helico-axial pump (HAP) operating satisfactorily at intake GVFs up to 97%. The findings increase capabilities of field engineers and operators to boost and maximize production from high gas-content wells. The HAP tested had a housing outer diameter of 4.00-inch and operated at a rotational speed of 6000 revolutions per minutes (RPM). Air and water were the test fluids with the water volume flow rate held constant at 63 and 143 barrels per day (BPD), while the air volume flow rate at pump intake was varied from 550 to 3480 BPD, respectively. Intake pressures varied from 14 to 76 psig, with average temperature through the HAP of 20°C. The corresponding discharge pressures and pressure boosts were recorded for each test point of observed stable pump operation. The results showed that the HAP had stable operation during the tests for intake GVF range from 85% to 97%. Pump discharge pressures for this range of high intake GVF varied from 21 to 89 psig. The corresponding boost pressures across the HAP all had positive magnitudes indicating that at such high- speeds, the HAP was still able to add energy to the fluid even with the high gas content at intake. Analysis at fixed intake pressure with varying GVFs showed that the pressure boost decreased with increasing intake GVF. For instance, at 33 psig intake pressure, an 11% increase in intake GVF from 85% to about 95%, decreased the HAP pressure boost by about 21%. In conclusion, running a HAP at high speeds with suitable component features can result in stable pump operation and enhanced pressure boosting in high- GVF flows. The findings from this test indicates the HAP potentially has a wide operating envelope and can be optimized and scaled up to meet field production requirements. This study mainly highlights the importance of operating HAPs at high speeds of up to 6000 RPM. The wider operating envelope of the HAP provides a potential application to handle more gas in the field. This architecture opens up opportunities for field operators, and engineering personnel to maximize hydrocarbon production from their very high-gas content field assets, thereby increasing the economic bottom-line for the stakeholders.