天然气油基水合物浆液流动实验

An experimental study of the hydrate blockage in the oil-dominated flow system

为了解决高压油气混输管道中天然气水合物堵塞的问题,利用中国石油大学(北京)新建的中国首套高压(设计压力15 MPa)天然气水合物实验环路进行了天然气油基水合物浆液流动实验,探究了压力、流量等因素对天然气水合物浆液流动、堵管趋势以及堵塞时间的影响,并利用实时在线颗粒粒度仪监测了天然气水合物浆液生成过程中体系内天然气水合物颗粒粒径的变化趋势。实验结果表明:压力越高,天然气水合物堵管时间越短,天然气水合物的堵管风险增大;增大流量可以减缓天然气水合物堵管趋势,降低天然气水合物堵管的概率,但存在"临界最低安全流量"现象,即当流量大于某值时,天然气水合物不会发生堵管,流体以浆液的形式在环路中流动。反之,则会发生天然气水合物堵管事故;在天然气水合物生成过程中天然气水合物颗粒的粒径(弦长)分布会发生显著变化,天然气水合物颗粒间的聚并是导致天然气水合物浆液发生堵管的主要原因。

This paper aims to deal with the plugging of natural gas hydrate in the high-pressure oil-gas mixed transmission lines.Therefore,an experimental study was conducted of oil-dominated flow in the Chinese first set of high-pressure natural gas hydrate experimental loop which was newly built by China University of Petroleum in Beijing.In this experiment,we explored the impacts of pressure,flow rate,etc.on the natural gas hydrate slurry flow,plugging tendency,and the plugging time.And a real-time online particle size analyzer was employed to monitor the variation tendency of hydrate particle diameters during the process of hydrate slurry generated within the system.The following findings were obtained.（1）Higher pressure will quicken the plugging,which increases the risk of hydrate plugging.（2）Increasing the flow rate can slow down the tendency of hydrate plugging to reduce the probability of hydrate blockage;But,there was a phenomenon called the ＂critical minimum safety flow rate＂,that is,if the flow rate is greater than a certain value,hydrate plugging will not occur,and the fluid flows in the loop in the form of slurry,otherwise,hydrate blockage will occur.The agglomeration of particles during the hydrate formation process is the main reason for hydrate slurry blockage.