Pigging Simulation Research Of Waxy Crude Oil Pipeline

Waxy crystals precipitate on the pipe wall during the period of pipeline running.The hardness of sediments increases with time,which results in the nature difference of radial position.When wax resistance outweighs driving force,there exists plugging risk.Therefore,writing software to predict wax deposition thickness and hardness,as well as researching the variation of wax resistance plays an important role in decreasing plugging risk and ensuring steady running of pipeline.Calculation method of wax resistance is proposed on the base of wax plug increasing research.The forming of wax plug can be judged by the relationship of discharge flow and stripped wax amount per unit length pipeline.Method of judging wax plug risk is raised according to the relationship of wax resistance and motive force.Wax resistance variation when wax plugging grows is confirmed on the base of Hongjing pipeline and Linpu pipeline wax plug accidents.The verification result shows that wax resistance per unit area pipeline remains stable.Waxy crude oil pipeline wax deposition and pigging prediction software is written according to wax deposition model of CUP,as well as pigging research findings.Function of software includes prediction of wax deposition rate and thickness,prediction of paraffin content at different radial position,prediction of pigging efficiency and stripped wax amount by different kinds of pig,judging the forming of wax plug according to critical condition.Wax deposition prediction result of software using field data of Cezhen pipeline is confirmed.Prediction wax deposition amount dovetails its actual counterpart,with the error of 17.9%.