天然气水合物在输气管道中的生成预测及防治技术研究

Research on Formation Prediction and Prevention Technology of Natural Gas Hydrate in Gas Transmission Pipelines

输气管道在管输过程中因水合物引发的流动保障问题不容忽视,水合物会造成管道及附件设备堵塞,影响管存及管输量。针对这一问题,以某国际输气管道为例,采用修正的双流体模型,通过求解相间传递的状态方程,并耦合各节点的物性参数模拟结果,得到不同流动状态下的水力、热力特性,用于预测投产初期水合物生成区域、管道析水区间、水合物生成量及沉积分布情况,并对抑制剂效果进行了评价。结果表明,当含水量超过100 mg/m^(3)时,管道在128.84 km后开始析出游离水;水合物生成量随时间延长呈对数增长;水合物主要沉积在低洼上坡段,沉积程度与上坡段高差有关,还与上游管道的高差、坡长、坡度等因素相关;当添加40%~50%的乙二醇时,可有效防止水合物的生成。研究结果可为输气管道流动保障提供实际参考。

In the process of pipeline gas transmission,the flow assurance problem caused by hydrate should not be ignored.Hydrate causes the blockage of pipeline and accessory equipment,and affects the pipeline storage and transmission capacity.To solve this problem,taking an international gas transmis-sion pipeline as an example,the modified two-fluid model is adopted to obtain the hydraulic and ther-mal characteristics under different flow states by solving the state equation of interphase transfer and cou-pling the simulation results of physical parameters of each node,which can be used to predict the hy-drate formation area,pipeline water seepage area,hydrate generation,and deposition distribution at the initial stage of production as well as evaluate the inhibitor effect.The results show that when the wa-ter content is more than 100 mg/m^(3),free water begins to precipitate in the pipeline after 128.84 km.The hydrate production increases logarithmically with time.Hydrate is mainly deposited in the low-ly-ing upslope section,and the degree of deposition is related to the height difference of the upslope sec-tion,as well as the height difference,slope length,and slope gradient of the upstream pipeline.When 40%~50%glycol is added,hydrate formation can be effectively prevented.The research results can pro-vide a practical reference for the flow assurance of gas pipelines.