Evaluating Operational Capabilities of High-Speed Gas Handling for Downhole Oil Production

Abstract

High-speed electric submersible pumps (ESPs) for downhole oil production typically operate with rotational speeds in excess of twice that of conventional pumps. These pumps need gas handlers to ensure satisfactory operation at higher gas volume fractions (GVFs). This study presents an evaluation of the operational capabilities of high-speed gas handling. Knowledge of these capabilities aids production engineers and field operators to make more informed decisions for efficient downhole oil production operations. The evaluation was performed for high-speed gas handling for downhole pumps with 2.17, 3.19, 338, 400 and 538 series housing sizes. These pump size architectures were for typical casing/liner diameters varying from 4.5" to 7.0". In the evaluation, the inlet pressure was fixed, whereas the GVF and rotational speeds were varied. The GVF range was from 0 to 0.75, and the rotational speed varied from 3500 to 12000 revolutions per minute (RPM). The total volume flow rates varied from 4500 barrels of fluid per day (BOFPD) to upward in excess of 10000 BOFPD. The results show that for a given inlet pressure increasing the rotational speed of a gas handling device increases its capability to process and pump the downhole fluids. There is also a tendency for higher gas handling capability when the rotational speed of the device is fixed and the dimensional size of the downhole equipment is varied. The observation will tend to suggest that for a given GVF, the gas handler operating at a higher rotational speed would be more tolerant to gas than the unit operating at a lower rotational speed. There is a tendency for the operational capability of the gas handler to be limited by the rotor dynamics and mechanical component, such as the shaft. This limitation will tend to depend on the size of the gas handling unit. These observations suggest an upper operation limit of the high-speed gas handling system can be attributed to a limitation of some of the specific system components. This study highlights the importance of understanding capabilities of high-speed gas handling systems, which are needed for high gas content wells for downhole oilfield production operations. Knowing the parameters that limit high-speed gas handling is beneficial for deciding which device is most appropriate to use in a particular well. Such knowledge is vital for the operator to make strategic decisions to efficiently produce hydrocarbons using the field asset, and maximize the economic bottomline for the operator.