Field Application Design for a Novel Motorized Submersible Pump

Abstract Production operations sometimes require the use of Electric submersible pumps (ESPs) to lift fluids from the reservoir to surface. To remedy some of the field installation challenges associated with long equipment lengths, a new motorized pump was previously designed and potential performance results presented. The current work showcases the mechanical component architecture employed to ensure the functional capabilities of the new motorized pump were achieved, similar to conventional ESPs but with shorter overall length. The new motorized pump has a 5.62-inch housing diameter. One of the main areas addressed was the thrust handling capability of the pump given the absence of a seal or protector section, compared to conventional ESPs. A review of methodologies to handle pump thrusts was performed and a method incorporated to suit the specific pump layout. The critical speed of the system was also considered and required integrating shorter spans between support radial bearings. Finally the assembly architecture to integrate all the components into a downhole unit was investigated to ensure easy installation in the field. The results showed that the 45-stage motorized pump must handle a total of about 20 kLbf of downthrust load based on the maximum pressure boost/head the pump can generate. Given that this load will be excessive for one thrust bearing, a system of thrust surfaces were introduced to facilitate distribution of the thrust load throughout the pump. This method is different from current conventional methods of handling thrust in ESPs, and the results showed that the stress loads on the thrust surfaces were within acceptable limits. The pump operating speed for the motorized pump was 4200 RPM. Based on the mid-span distances of the pump radial bearings, the first critical speed of the system was estimated to be more than 40 times the pump operating speed. This implied that within the pump operating envelope, the system will not experience any vibration resonance phenomenon that can be detrimental to the system operation. The checks on the stress load of all critical components showed they were all within the working loads. A minimum safety factor of 2 was observed throughout the system analysis. This study highlights the benefits of incorporating a different approach of component design to enable feasibility of the new motorized pump. The implemented system architecture enabled the motorized pump to have the same functionality as conventional ESPs, but with a much shorter total length. The advantage for the field operator includes easier handling for field personnel and, reduced bending stresses during field installations. This decreases equipment failure and increases operating efficiency for the field.