Ultra-High-Speed High-Gas-Volume-Fraction Pump Development

Abstract

Abstract Wellbore conditions below bubble point pressure in high gas-oil-ratio (GOR) wells result in very high amount of free gas at the inlet of Electric Submersible Pumps (ESP). Conventional multiphase pumps have limitations handling free gas exceeding 75% intake gas-volume-fraction (GVF). The objective of this work is to develop and field test a new Ultra-High-Speed High-Gas-Volume-Fraction (UHS HGVF) pump system. The ultimate goal is to facilitate sustained production from wells experiencing high-GVF production challenges. The UHS HGVF pump is a new type of submersible pump with an architecture being investigated to boost hydrocarbon production from high GOR oil wells. The principle of operation is based on turbulent friction, in which a spatial vortex flow is formed, rotating together with the rotor and moving along its axis. The pump housing diameter is 4.00 inches and operates at a shaft rotational speed in excess of 3.5 times those of conventional pump systems. Hydraulic design, computational fluid dynamics analysis, prototyping and physical testing were performed to optimize the performance of the UHS HGVF pump. The results show that the new pump architecture is capable of handling gas-liquid mixtures with intake GVF well beyond the 75% GVF limitation of conventional multiphase pumps. This was mainly attributed to the pump features, which impart the required amount of energy and turbulence to the gas-liquid mixture but simultaneously minimizes separation of the gas and liquid phases. These combined effects facilitated thorough mixing of the gas-liquid streams ensuring the pump provided sufficient pressure boost for the downhole setting depths which the system was designed. The system was also observed to have a high capability of sand tolerance and thrust handling. The ruggedized system has the required attributes to withstand operation in gassy field conditions. This work presents a conceptually new approach to pump development with the aim of overcoming hydrocarbon production challenges in wells with very high free gas at pump intake. The UHS HGVF pump widens the operating envelope to produce a high GOR well, thereby achieving production gains in gassy conditions, where conventional systems are limited. The system therefore serves as an essential artificial lift tool to handle production in increasing numbers of extremely gassy wells.