清管段塞预防技术在海底混输管道上的应用

Application of pigging slug prevention technique in multiphase subsea pipeline

在对天然气凝析液海底混输管道进行清管时,清管段塞会对下游的生产工艺流程产生一定的冲击。通过采用OLGA软件对某海管不同输量工况下管输压降及管内滞液量进行预测,制订出如下清管方案:在清管前通过增加生产井数量或调大采油树油嘴以增加海管的输量,降低管内的滞液量;清管器发出后,再关闭部分生产井或减小油嘴开度,以减慢清管器的行驶速度,从而减小管内积液,达到减小清管段塞和延长清管段塞泄放时间的目的。研究表明:该方案可将段塞容积减小至58 m^3,同时段塞流量降低至以平均输量工况清管时的45%,满足了段塞容积小于平台上段塞流捕集器的有效储存容积(60 m^3)的要求。

During pigging operation of multiphase subsea pipelines containing natural gas condensate,pigging slug will result in certain impact on the process of pipeline downstream production process.Taking an subsea pipeline as an example,the pressure drop and the liquid hold in the pipeline were predicted by OLGA software under different flowrate conditions,a pigging scheme was determined,that is,increase the number of production wells or enlarge the oil nozzle of the oil production tree before pipeline pigging to increase subsea pipeline throughput;some production wells are closed or the nozzle opening is reduced after the pig being dispatched;so as to slow down the pig running speed,thus reducing the liquid accumulation in the pipeline and the pigging slug and prolonging the discharge time of the pigging slug.It is indicated that the slug volume can be reduced to 58 m^3,and the slug flow rate can be reduced to 45%of that in average throughput condition,which satisfies the requirement that the slug volume is less than the effective storage volume(60 m^3)of the slug collector on the platform.