涪陵页岩气田集气干线积液规律研究

涪陵页岩气田集气干线位于山地丘陵地带,地形起伏较大,管内流动复杂,能量损失严重,在低洼处易产生积液,从而增加管线输送阻力,降低输送效率,严重影响管线安全运行。从集气干线积液机理出发,利用Fluent软件对管内气液两相流场进行模拟计算,基于液膜模型假设,建立考虑液膜不均匀分布的临界携液流速计算方法,计算结果与模拟结果吻合,均表现为倾斜角50°左右最难携液。针对管线内气体携液量难以估算的问题,引入遗传算法,以管线计算压差与实际压差误差最小为优化目标,对管段内液体流量进行拟合,在此基础上建立管线积液量计算方法。以涪陵页岩气田某管段为例进行了实例计算,结果表明积液量计算结果与清管结果吻合,积液主要发生在输气量较小、倾斜角较大的A-B段和C-D段。

Liquid Loading Law Study of Gas Gathering Trunk Line in Fuling Shale Gas Field

The gas gathering trunk line of Fuling Shale Gas Field is located in Hilly area.The pipeline fluctuation is large,the flow in the pipeline is complex,and the energy loss is serious.It is easy to produce liquid loading in low-lying areas,which leads to the increase of pipeline transmission resistance and the decrease of transmission efficiency and seriously affects the safe operation of pipeline.Starting from the liquid loading mechanism of gas gathering trunk line,Fluent software is used to simulate the gas-liquid two-phase flow field in the pipeline.Based on the assumption of liquid film model,a calculation method of critical liquid carrying velocity considering the non-uniform distribution of liquid film is established.The calculated results are in good agreement with the simulation results,and it is the most difficult to carry liquid when the inclination angle is about 50 degrees.Aiming at the difficulty of estimating the liquid carrying capacity of gas in pipeline,a genetic algorithm is introduced to fit the liquid flow rate in pipeline with the objective of minimizing the error between the calculated pressure difference and the actual pressure difference.On this basis,a method for calculating the liquid loading volume of pipeline is established.A pipe section of Fuling Shale Gas Field is taken as an example,and the simulation results show that the calculation results of liquid loading volume are consistent with the results of pigging.Liquid loading mainly occurs in A-B section and C-D section with small gas transportation volume and large inclination angle.