Analysis Of The Motion Process Of The Pigs In Liquid Included Gas Pipeline

With the development of China’s oil and gas industry,the research and application of multiphase transportation technology is increasingly important.As the distance of liquid included gas pipelines increasing and pipeline routing is fluctuating and changing,the related pigging technology has been correspondingly placed in an important position.In order to ensure the smooth production and safe and stable operation of liquid included gas pipelines,the study of the pigging rules and the analysis of the movement process of pigs play an important role in the safe and efficient conduct of pigging operations.Therefore,this paper studies and establishes a pigging model from a perspective of engineering adaptability,with designing its quasi-steady state algorithm.Besides,this paper uses the program to simulate pigging process and analyzes the motion process of pigs.Firstly,this paper has investigated the methods of flow pattern judgement,liquid holdup and pressure drop calculation for two-phase flow.Sukhov formula and J-T effect are used to calculate temperature drop and three methods of two-phase flow hydrodynamic calculation are selected to establish a quasi-steady-state hydro-thermodynamic model,coupling with phase-behavior model.By comparing the model simulation results with OLGA,one of the three models with the least error and highest applicability is selected.Then,on the basis of previous research,taking the liquid included gas pipeline with topography relief as the research object,this paper analyzes the force of pig in the pipeline,establishes the physical force model,derives the mathematical model of pigging by coupling with quasi-steady-state hydro-thermodynamic model of two-phase flow,and use Java language for its programming.The program can not only simulate the running time,running position,velocity of pig and rules of inlet pressure change,but also can track the length of pigging slug,simulate the distribution of two-phase fluid parameters such as pressure and liquid holdup at various time in the pigging process.Finally,using the pigging procedure in this paper to simulate engineering examples,analyze the pigging operation law and compare the pigging parameters obtain by the simulation with OLGA.In general,from the perspective of engineering adaptability,the pigging procedure studied in this paper is simple and feasible,and it can meet the requirements of engineering precision and provides technical basis and reference for engineering application.