Advanced computer simulations for pump stage design enable an efficient way to design and evaluate pump performance. Simulations also provide detailed structural behavior (e.g., stress, modal analysis), temperature analysis and performance at various flow regimens (multiphase flow). Finite element analysis (FEA) and computational fluid dynamics (CFD) can be coupled with multi-disciplinary design optimization (MDO) in pump stage design practice, becoming a more helpful tool than traditional trial-and-error approaches. These tools are used to accelerate the design process of new pump stages for electric submersible pumps (ESP).

A simulation-based design was used to develop a hybrid gas-handling stage. It has been demonstrated that a hybrid stage manages a higher gas volume fraction (GVF) through production tubing as well as achieves a rising head across the operating range. The hybrid comprises an axial-flow stage and a mixed-flow stage as a set. An axial-flow stage is designed at high flow rates to push the liquid and gas phases together. The two-phase fluids then enter a mixed-flow stage, which generates a head with a reduced gas lock. One of the challenges is achieving a rising head curve across the operating range. The head curve of an axial-flow pump often constantly rises, leading to a wide operating range. Combining an axial-flow stage with a mixed-flow stage achieves a rising head and a wider flow range. Computer-based, two-phase flow modeling was used to accelerate and optimize the design of hybrid stages. As a result, this hybrid stage exhibits a high-efficiency rising head across the operating range and high gas-handling capabilities.

The prototype of this new hybrid stage was manufactured by 3D metal printing. Additive manufacturing technology has a shorter processing time, a lower scrap rate and is more affordable in the prototype phase. Material selection was considered to meet the design requirements for the testing system.

In this study, a new 4-in. hybrid concept was developed to meet the need of high-GVF wells. Pump performance testing and two-phase flow testing with the prototype pump was performed, and the results were compared with simulation models. Simulation models, well authenticated by thorough tests, provide reliable and effective stage-design tools, which provide a validation of a project's viability. The prototype has demonstrated capabilities to pump above 75% GVF without gas locking. Currently, the hybrid stage pump is under the product development phase based on the encouraging results on handling high percentage of gas.

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