A New Methodology to Analyze Fluid Pound in Sucker-Rod Pump Systems: Phenomenological Approach

Abstract

Sucker-rod pump system is the most used artificial lift method in the world. Although used for more than a century at industrial scale, its working is not completely understood. The main tool employed to analyze operation is the dynamometric charts which is obtained with equipment already producing. A major problem found in these systems is the fluid pound that indicates a partial barrel filling with the producing fluid. This specific fluid pound problem is detectable by this tool but after the event occurs. In order to offer a tool at design stage, this study proposes an alternative method based on phenomenological flow modeling and rigorous geometry details. The method is based on Fluid Structure Interaction (FSI) technique in which both Computational Fluid Dynamics (CFD) and Rigid Body Analysis are solved simultaneously. The geometry used was comprised in the standing valve part of the subsurface pump. At the present stage, the model considers isothermal, incompressible single-phase turbulent flow. The aim of the methodology is to calculate the volume of fluid admitted into barrel at upstroke phase. It is proposed a fill parameter, which represents the fraction of filled barrel volume, to indicate the existence or not of fluid pound problem. The methodology allows to investigate several operational parameters. In the present paper, the stroke length, pressure intake and cycles per minute were investigate. The tendencies previewed by the methodology were in agreement with field observations, demonstrating the potential of this tool.