Abstract: Electric submersible pump (ESP) is one of the most common artificial lift techniques. However, when it is applied to heavy oil wells, due to the influence of high viscosity, the performance curves of ESP deviates from the common ones, which caused the effective application window of ESP. Therefore, the centrifugal pump's structural parameters are designed under water flow condition, which is difficult to adapt to the high viscosity environment of heavy oil wells. In view of the above problems, based on the computational fluid dynamics (CFD) numerical simulation method, we study the pressurization characteristics of ESP under the high viscosity condition. The results show that with the increase of fluid viscosity, the frictional force increases, and the interaction effect also shows an increase trend. However, the pressure difference between the impeller inlet and the diffuser outlet decreases, which leads to the flow rate decrease. Meanwhile, the flow regime inside ESP changes from turbulent flow to laminar flow, and recirculation flow area inside the impeller and diffuser blades decrease. Under the same viscosity condition, the head of centrifugal pump decreases with the increase of displacement. Under the same liquid flow rate, the head of centrifugal pump decreases significantly with the increase of viscosity. Based on factor analysis, by taking the effect of viscosity into consideration, the structural parameters of the centrifugal pump are optimized. The optimal structures are as follows: inlet width is 16.6 mm, blade number is 6 pieces, outlet width is 21.9 mm, and blade inclusion angle is 60o. Compared with the original centrifugal pump, when the viscosity is 400 mPa·s, under the submersible electric pump works in allowable flow rate range, the maximum increase of head is 28%.

Key words: viscosity, electric submersible pump, CFD, performance curves, optimization of structural parameter