| Motion Law of standing valve, pump dynamic full extent and limits of minimumsubmergence pressure are important foundation of parameters optimization design for suckerrod pumping system. Ground motion of pumping unit and movement characteristics ofdownhole sucker rod string are comprehensively considered in this paper. The motion law ofdownhole plunger is obtained, which provides a basis for describing the relevant motion lawof standing valve in downhole pump. The numerical simulation of process of fluid flowingthrough standing valve based on computational fluid dynamics commercial software obtainsthe distribution of pressure field and velocity field inside pump, and we analyze the influenceof standing valve opening degree, rates of flow and fluid properties on local resistance loss forstanding valve. The flow coefficient curves under different opening degree are obtained, andwe get binary relevant formula between discharge coefficient and reynolds number andopening degree of standing valve by using nonlinear fitting method. On this basis, we analyzeforce condition of standing valve in upstroke and establish mathematical model of motion lawof standing valve. It is solved by using numerical method, and factors affecting the motion ofvalve ball has been analyzed contrastively. Comprehensively considering the gas in pump andfluid properties, combined with opening degree of standing valve and the flow coefficientcalculation method, the computational model of dynamic full extent for sucker rod pump isestablished. Numerical method is used to solve the model. The influence law of swabbingparameters and fluid physical properties on full extent has been analyzed. At last, the methodto determine the minimum submergence pressure for sucker rod pumping based on full extentis established, and sensitivity analysis for the minimum submergence pressure is completed. |
