Modeling the Effect of Transient Viscous Forces on Sucker Rod Pump Performance and Run Lift

The sucker rod pump is commonly used to lift heavy oil wells under thermal production to maximize the flow rate due to its high efficiency and reliability. However, rod fatigue and possible failure are commonly encountered when rod design does not incorporate the appropriate loads, especially in high-viscosity conditions. Although the existing commercial design tools solve the wave equation to predict rod string life, they do not incorporate the effect of liquid viscosity, resulting in prediction discrepancy and inappropriate rod design and pump operation. The aim of this study is to propose a theoretical model to investigate the effect of the transient frictional forces acting on sucker rod pump subsurface components, i.e. rod and pump. Furthermore, a sensitivity analysis case study is carried out to investigate the effect of various flow and design parameters on the rod top-of-section stresses, rod buckling tendency, and fatigue life. This work provides a comprehensive understanding of the underlying interaction between fluid flow behavior and rod dynamics.