Simulation of valve operation in a down-hole pump

The research article 'Simulation-aided identification of mid-cycle valve closure in a down-hole pump' has been published in Elsevier's Journal of Fluids and Structures (Volume 91, November 2019, 102774).

Abstract

In this work we present a combined finite element model of a standing valve and a travelling valve in a down-hole pump used in oil extraction. The model allows the self-consistent simulation of several pump cycles without the need to assume artificial coupling conditions between two separate valves, at the cost of large variations in length of the system during a pump cycle. We discuss how to overcome the difficulties associated with such a model, such as avoiding solid–solid contact during valve closure and how to correctly implement the plunger kinematics. We then compare the behaviour of a down-hole pump operating according to ideal plunger kinematics to one with realistic plunger kinematics that are dominated by the characteristic oscillations of the sucker rod. In the latter case, we observed that transient reductions in the plunger velocity can lead to mid-cycle valve closure. This poses a threat in terms of additional damage to the components due to ball impacts and fluid pressure drops, which could in turn lead to undesirable accumulation of gas.

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