Prediction of the Driving Force for the Bidirectional Pig Based on the Cantilever-Kelvin Combination Model

Abstract

The precise prediction of the driving force has significant meaning in preventing blockage accidents in oil and gas pipeline pigging engineering. In this paper, a novel prediction model is established for the typical bidirectional pig with the method of combing a theoretical model and finite-element (FE) simulations. The three-dimensional (3D) FE model of the pigging operation is established first, which is verified with a custom-built experiment from the literature. Then, friction characteristics such as deformation and contact area are analyzed based on the established model. The flexural-cantilever model and creep-Kelvin model are used to describe the bending and compression deformation, respectively, and a mechanical model, named the cantilever-Kelvin combination model, for presenting the stress state of the sealing disk, is built according to the simulation results. Finally, a prediction model of the driving force is established based on the cantilever-Kelvin combination model. The research results indicate that the bending deformation and contact area have a similar variation trend as the interference under different friction coefficients. A series of case analyses are conducted to verify the accuracy of the established prediction model, which is proven to satisfy the arbitrary interference and friction coefficient conditions.