超高分子聚合物驱提高高盐稠油油藏采收率机理及现场应用

Investigation on Mechanism and Effect of Ultra-high Molecular Polymer Flooding for Enhancing Recovery in High Salinity Heavy Oil Reservoirs

针对常规聚合物(部分水解聚丙烯酰胺HPAM)无法满足高盐稠油油藏采收率要求的问题,以胜坨油田二区东三4砂组高盐稠油油藏为研究对象,实验结合数值模拟分析了超高分子聚合物驱和常规聚合物驱的提高采收率机理。研究表明,超高分子聚合物黏度、黏弹性,耐盐性以及高温下的稳定性均优于常规聚合物,采用超高分子聚合物驱油更容易实现活塞驱油;相比于常规聚合物,分子间排列更加致密且互相缠绕,分子间缔合作用力远大于常规聚合物,表现出很强的抗盐、抗拖拽能力,具有很强的调剖能力;CMG数值模拟结果表明,采用超高分子聚合物驱提高东三4砂组油藏采收率具有见效早、降低含水率效果好的优点。对于东三4砂组油藏,采用超高分子聚合物驱(DQ-3500)相对于常规聚合物驱(8^(#)HPAM)采收率提高了1.74%。该研究成果对于采用超高分子聚合物驱提高高盐稠油油藏采收率的推广应用具有重要意义。

In view of the problem that conventional polymer(polyacrylamide HPAM) cannot meet the requirements of recovery in high-salinity heavy-oil reservoirs.Taking the high salinity heavy-oil reservoirs of Dongsan 4 Sha Formation in Shengtuo Oilfield Area 2 as the research object,combined with numerical simulations the enhanced oil recovery effects of ultra-high polymer flooding and conventional polymer flooding was analyzed.The results show that:the viscosity,viscoelasticity,salt resistance and high temperature stability of ultra-high polymer are better than those of conventional polymer,and it is easier to realize piston oil displacement by using ultra-high polymer oil displacement;Compared with the conventional polymer,the intermolecular arrangement is denser and intertwined,and the intermolecular association force is far greater than that of the conventional polymer,showing strong salt resistance and drag resistance and strong profile control ability;The results of CMG numerical simulation show that the ultra-polymer flooding has the advantages of quick effect and good water cut reduction effect to enhance oil recovery of Dongsan 4 sand group.In the end,the recovery ratio of polymer flooding is increased by 1.74% compared with conventional polymer flooding.The research results are of great significance for the popularization and application of ultra-high molecular polymer flooding to enhance the recovery ratio of high-salt heavy oil reservoirs.