| With the developing of our nation’s natural gas industry,the wet gas gathering and transportation process is facing a number of problems,especially the accumulation of liquid in gathering and transportation pipelines in complex terrains.The existence of the liquid will reduce the area of passage in gathering and transportation pipelines,increase the energy consumption of the gathering and transportation pipelines.It also induces the hypsography slug flow and accelerates the erosion progress in the pipelines.Therefore,it is essential to study the influence factors,build the pressure drop prediction model in gathering and transportation pipelines with liquid.The generation,development and distribution rules of the liquid in the terrain pipeline will be investigated and a reasonable pigging period will also be proposed.The aim is to achieve safety and high efficient of gathering and transportation pipelines in gas fields.The method of combining theoretical analysis,field investigation and numerical simulation was applied during the study process.The liquid accumulation prediction model in gathering and transportation pipelines is developed by using multi-phase flow kinetic theory.The information of the liquid holdup,pressure drop and temperature distribution were obtained.The prediction model is verified and improved with the help of the field data.The pigging period optimization model was also proposed and the best pigging period was determined.This article presents the concept of critical liquid quantities is proposed and the information of liquid distribution characteristics in 7 pipelines were successfully predicted.we also studied the influence factors of the liquid accumulation in case of start or or intermediate shut down of the pipeline.The influence of flow patterns such as stratified flow,slug flow,bubble flow was considered in the prediction model.It is found the prediction result of liquid hold up,pressure drop agree well with the field data. |
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