海上中低渗油藏多功能纳米增注体系性能评价及应用

目的 目前部分海上中低渗油藏薄互层较为发育,具有孔隙结构复杂、局部物性差、层内非均质强等储层特征,导致整体呈现“注不进水,采不出油”现状,严重制约了油田开发效果和储量动用程度的提高。针对这些问题,提出了一种新型纳米增注体系,为海上油田中低渗油藏注水开发提供一套有效的解决方案。方法 通过室内实验性能评价方法对体系润湿性、除垢性能、渗透率改善性能进行研究。结果 纳米溶液处理后岩心由亲水变为疏水,平均岩心润湿角提高20°左右,使流过的水分子发生速度滑移,减少流动阻力;纳米溶液有助于剥离后的有机垢分散,洗脱率达到92.3%,避免剥离后有机垢的二次沉淀堵塞,并且能有效溶蚀矿物,溶蚀率达到43%,起到很好的解堵除无机垢效果;岩心经过纳米溶液驱替后,平均渗透率提高32.6%,平均注入压力下降35.9%。结论 现场应用结果表明,该技术可显著提高注水井吸水能力,措施后注入压力下降46.7%,注入量增加8倍,吸水指数提高12.2倍,有效期是常规酸化的4倍以上。

Performance evaluation and application of multifunctional nano injection system in offshore medium and low permeability reservoirs

ObjectiveAt present, thin interlayers in some offshore medium and low permeability reservoirs are relatively developed, with complex pore structure, poor local physical properties, strong in-layer heterogeneity and other reservoir characteristics, which causes the overall situation of "no water injection, no oil production", and seriously restricts the oilfield development effect. Accordingly, a new nano injection enhancement system is proposed. It is necessary to develop new multifunctional augmented injection materials to meet the requirements of high-efficiency pressure reduction and long-term injection increase. Methods The wettability, scale removal performance and permeability improvement performance of the system are studied through indoor experimental performance evaluation method. ResultsThe results show that the core is changed from hydrophilic to hydrophobic after nano solution treatment, and the average core wetting angle is increased by more than 20°, which makes the flowing water molecules slip and reduce the flow resistance. The nano solution helps to disperse the organic scale after stripping, with the elution rate reaching 92.3%, avoiding the secondary precipitation blockage of the stripped organic scale, and can effectively dissolve minerals, with the dissolution rate reaching 43%, playing a good role in unblocking and removing inorganic scale. After the core is displaced by nano solution, which increases the average permeability of artificial core by 32.6%, decreases the average injection pressure by 35.9%. ConclusionsThe field application results show that the technology can significantly improve the water absorption capacity of water injection wells. After using the measures, the injection pressure decreased by 46.7%, the injection volume increased by 8 times, the water absorption index increased by 12.2 times, and the effective period was over 4 times than that of conventional acidification.