流花16-2油田海底管道清管方案优化研究

Study on optimization of pigging scheme for submarine pipeline in LH16-2 oilfield

流花16-2油田投产初期,海底管道按原规划需每5天实施一次清管作业,但现场每次清出的含蜡杂质较少。为保证清管作业的安全,清管时需将海底管道输量由4957 Sm^(3)/d降低至4512 Sm^(3)/d,高频次的降产清管作业造成油田产量过多牺牲。为了在保障油田安全生产的前提下实现提质增效,选取冬季典型工况,对流花16-2油田海底管道清管方案开展优化研究。结合各软件的优点,选用OLGA软件模拟流花16-2油田海底管道清管时管道沿线温度、压力变化规律,选用Pipeflo软件模拟稳态工况下管道沿线温度、压力分布情况,选用TUWAX软件预测管道内蜡沉积规律。结果表明:流花16-2油田海底管道冬季运行时,距离海管入口约19.7 km处开始结蜡;该油田需要清管的条件为海底管道已连续运行10天未实施清管作业或在产量未增加的情况下海底管道入口压力的增幅长时间超出0.05 MPa且呈继续增长的趋势;选取2 m/s作为清管器运行速度最大值,要求清管流量应不超过7500 Sm^(3)/d,现场原采用的“清管需减产”方案可优化为“清管不减产”方案,即清管时,按照流花16-2油田当前产液量4957 Sm^(3)/d,无需降低各井口总产液量,只需将发球置换泵流量由2640 Sm^(3)/d调整为2543 Sm^(3)/d。本研究为类似油田海底管道合理清管方案的制定提供了参考。

In the early production period of LH16-2 oilfield,the submarine pipeline pigging was carried out every five days according to the original plan,but the amount of wax-containing impurities removed each time at site was little.In order to ensure the safety of pigging operations,the submarine pipeline throughput should be reduced from 4957 Sm^(3)/d to 4512 Sm^(3)/d during pigging,which resulted in excessive production sacrifice in the oilfield due to the high frequency pigging operations with production reduction.To improve the quality and efficiency under the premise of ensuring the safe production of the oilfield,typical working conditions in winter were selected to study the optimization of pigging scheme for submarine pipeline in LH16-2 oilfield.Combined with the advantages of each software,OLGA software is used to simulate the variation of temperature and pressure along the submarine pipeline during pigging in LH16-2 oilfield,Pipeflo software is used to simulate the distribution of temperature and pressure along the pipeline under steady conditions,and TUWAX software is used to predict the wax deposition law in the pipeline.The results show that:when the submarine pipeline of LH16-2 oilfield runs in winter,wax begins to deposit about 19.7 km away from the inlet of the pipeline;the condition for pigging in this oilfield is that the submarine pipeline has been in continuous operation for 10 days without pigging,or the increase of the inlet pressure of the submarine pipeline exceeds 0.05 MPa for a long time and shows a continuous growth trend in the case of no increase in production;when selecting 2 m/s as the maximum pigging speed and the pigging flow is required not to exceed 7500 Sm^(3)/d,the scheme of“pigging needs to reduce production”originally adopted in the field can be optimized to the scheme of“pigging without reducing production”,that is,when pigging,according to the current liquid production of LH16-2 oilfield of 4957 Sm^(3)/d,it is only necessary to adjust the service displacement pump flow from 2640 Sm^(3)/d to 2543 Sm^(3)/d instead of reducing the total liquid production of each wellhead.This study provides a reference for formulating a reasonable pigging scheme of submarine pipeline in similar oil fields.