Dynamic modeling and analysis of sucker rod pumping system in a directional well

Abstract

The sucker rod dynamic model including the influences of rod-fluid-tubing viscous friction and rod-tubing Coulomb friction is developed. Considering the influences of the liquid inertia and plunger-barrel friction, downhole boundary conditions are determined. To improve the velocity and preciseness of simulation and prediction, a hybrid algorithm is proposed for solving the wave equation. This algorithm combines the implicit differential method applied in homogeneous sucker rod with the variable step differential method applied in the boundary node of composite sucker rod. Based on the model and the algorithm, the computer programs predicting the polished rod dynamometer card of sucker rod pumping system in a directional well are written. The results of simulation and prediction show that the modeling method is effective and the reliability of the model is verified. The model can provide a reference for pumping well fault diagnosis.