耐高温微乳液体系在特低渗-致密储集层中的渗吸机理

Imbibition mechanisms of high temperature resistant microemulsion system in ultra-low permeability and tight reservoirs

采用微乳液稀释法制备具有“壳核结构”的下相微乳液,优选耐高温体系并开展性能评价实验,明确体系在特低渗—致密储集层中的自发渗吸提高采收率机理,指导矿场油井微破裂吞吐试验。室内实验结果表明,“壳核结构”以阳离子-非离子表面活性剂为亲水外壳、3号白油为油相内核的微乳液体系(O-ME体系)渗吸采收率最高,其渗吸机理主要为:超低界面张力和润湿反转能力降低原油黏附功,提高渗吸驱油效率;纳米级尺寸“壳核结构”极易进入微纳米孔喉,扩大渗吸波及体积;显著的分散、增溶原油作用增强原油渗流能力,提高渗吸驱油效率。基于室内实验研究结果,在胜利油田YBD43-X506井开展O-ME体系微破裂吞吐矿场试验,开井生产后该井持续受效,日产液从1.4 t增至5.0 t,日产油从1.0 t增至2.7 t。

Lower-phase microemulsions with core-shell structure were prepared by microemulsion dilution method.The high temperature resistant systems were screened and the performance evaluation experiments were conducted to clarify the spontaneous imbibition mechanisms in ultra-low permeability and tight oil reservoirs,and to direct the field microfracture huff and puff test of oil well.The microemulsion system(O-ME)with cationic-nonionic surfactant as hydrophilic shell,No.3 white oil as oil phase core has the highest imbibition recovery;its spontaneous imbibition mechanisms include:the ultra-low inter-facial tension and wettability reversal significantly reduce oil adhesion work to improve oil displacement efficiency,the nanoscale“core-shell structure”formed can easily enter micro-nano pores and throats to expand the swept volume,in addition,the remarkable effect of dispersing and solubilizing crude oil can improve the mobility of crude oil.Based on the experimental results,a microfracture huff and puff test of O-ME was carried out in Well YBD43-X506 of Shengli Oilfield.After being treated,the well had a significant increase of daily fluid production to 5 tons from 1.4 tons,and an increase of daily oil production to 2.7 tons from 1.0 ton before treatment.