Study On The Calculation Model Of Liquid Holdup And Pressure Drop In Topographically Undulating Wet Gas Pipeline

In recent years,the study of wet gas pipe flow has become a common research topic in the process of onshore and offshore natural gas technology.Since oil exploration and development are often located in remote areas with complex terrain,the study of wet gas pipe flow must be combined with the terrain,and it should be studied from the actual working condition.For complex terrain conditions,in this paper,based on the multi-phase flow software and several classical combination models,the prediction models of flow pattern,section liquid content and pressure drop in the process of wet gas flow are established or optimized.Under the condition of undulating terrain,liquid accumulation is often formed in the low-lying part of the pipe in wet gas pipeline,and the accumulation of effusion will affect the conveying efficiency of the pipeline.In serious cases,the pipeline will be blocked and cannot operate normally.The formation of effusion is closely related to the flow pattern,section liquid content and pressure drop of the pipeline.Based on the main factors affecting the flow pattern,section liquid content and pressure drop of the wet gas pipeline,this paper analyzes the influence rules of each factor on these three factors,so as to further study the flow pattern,section liquid content and pressure drop.In this paper,the possible flow patterns in the gas-liquid two-phase tube flow are firstly analyzed,and the formation mechanism of each flow pattern in horizontal,up dip,vertical and down dip tubes is analyzed respectively.By combining the existing classical prediction models of pipeline flow patterns,a combination model suitable for predicting the flow pattern of wet gas pipe flow is obtained.For the section liquid content of wet gas pipeline,firstly,the influence factors of section liquid content are analyzed by using multiphase flow software OLGA.Then,combined with the algorithm,the prediction model of section liquid content of up dip,horizontal and down dip pipe is established by using the existing data,the prediction model and the existing models are evaluated.The result shows that the prediction model has higher precision and has certain value in field application.For the calculation of pressure drop,in this paper,based on the collected historical data of wet gas pipelines under complex terrain conditions,nine existing gas-liquid two-phase flow combination models and multi-phase flow software OLGA are used to calculate the pressure drop.The calculated results are compared with the actual data and the error is analyzed.The results show that,compared with other combined models,the EF model shows good prediction performance,while the calculation error of OLGA is relatively large and about 20%,which indicates that EF is of high application value in the calculation of pressure drop of undulating wet gas pipeline.