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现场清管作业时清管器经常被卡堵，严重时会影响正常生产。针对这一问题，文章对清管器的运动特征和堵塞机理进行分析，阐述了清管过程中可能引起清管器堵塞的原因，重点分析了天然气通过清管器节流生成水合物造成清管器堵塞。研究表明，清管器是以脉动方式向前推进的，清管器通过管线突变处、积液处或遇到杂物将减速或停止，天然气在清管器处发生节流效应，生成水合物堵塞。文章还提出了清管器冰堵工况预测方法，可以确定出清管器上游温度与生成水合物节流压差的关系，结果表明清管器上游温度越低,生成水合物的清管器上下游压差越小。该方法能够用于现场清管作业时清管器堵塞工况预测。

STUDY ON HYDRATE PLUGGING MECHANISM AND PREDICTION WHEN GAS PIPELINE PIGGING 1)

The pig is blocked frequently when pipeline pigging, which will influence the normal operation due to severe plugging sometimes. According to the moving features and the hydrate plugging mechanism of pig, the reasons that may cause pig plugging during pipeline pigging are explained. The major one of the reasons is the hydrate produced by throttle while gas passes through the pig causes pig plugging. The study shows the pig moves by pulsating mode. The pig will decelerate or stop when it passes through the points of sudden change, liquid or impurities cumulating in the pipeline, and the gas will produce hydrate plugging since the throttle effect happens at the pig. It is proposed the prediction method of pig plugging, which can determine the relationship between the upstream temperature and the throttle pressure difference to produce hydrate. The results show the lower the upstream temperature is, the smaller the throttle pressure difference to produce hydrate is. The method can be used to predict the situation of pig plugging when field pigging job is conducted.