The study of hydromechanical characteristics of a well jet pump

A principle is proposed for the joint analysis of the hydrodynamic and strength characteristics of the elements of a downhole oil jet pump. Using ANSYS software, a 3D model of the ejection system was constructed, with is the geometric space limited by the boundary surfaces drawn through the annular section of the ejection system’s annular space, the suction line connecting the receiving chamber of the jet pump with the sub-packer diagonal and the outlet section diffuser. Fluid and solid mesh models were generated using virtual topology tools and a condensed layout of calculated finite elements in places of complex geometry and high pressure gradients. Stress in the body elements of the jet pump is caused by the difference in pressure acting on the outer and inner surfaces, accompanied by changes in the configuration of the flow path. The distribution of forces within the elements of the downhole ejection system was systematized: the working nozzle is subjected to tensile stress, while the receiving chamber, mixing chamber and diffuser of the oil jet pump are subjected to compressive stress. An increase in the magnitude of compressive stresses in the body elements of the jet pump toward the outlet section of the diffuser was calculated. Numerical modelling results indicate that the body elements of the receiving chamber and the outlet section of the jet pump diffuser are subjected to the heaviest loads. In experimental studies, the operating parameters of the ejection system corresponding to the occurrence of maximum stress compression in the jet pump components were determined. The maximum stresses in the body elements of the jet pump correspond to the minimum values of the injection coefficient of the jet pump, which are observed at the initial stage of formation fluid during the oil wells development. The results obtained support the recommendation to increase the internal diameter of the jet pump, which, under compressed well conditions, ensures an increase in its productivity without altering external overall dimensions.