Computational-Fluid-Dynamics model of a pair of coupled ball valves used in down-hole sucker rod pumps

Abstract

Down-hole sucker rod pumps are widely used in oil extraction. However, despite their longstanding employment, their operation in field conditions is not satisfactorily understood. We have developed a computational-fluid-dynamics (CFD) model of such a pump, based on the finite-element method (FEM). To the authors' knowledge, this is the first time that the dynamics of both the standing and the travelling valve are combined in a single computational FEM model. This allows one to simulate the opening and closing cycles of the two valves, and hence study the pump under more realistic conditions. Using our model, we have identified a new scenario that is associated with the interaction between the valves, which we refer to as midcycle valve closure, and which can potentially lead to several known damage mechanisms. We are able to predict the likelihood of the occurrence of the undesired mid-cycle valve closure and suggest ways to avoid this scenario by explicitly considering real pump cards.