针对非均质油藏注CO2驱油时普遍存在CO2易沿高渗层过早发生气窜,导致CO2驱提高采收率低,低渗层难以动用的问题,开展了CO2不同注入方式优选的室内试验,并对优选出的注入方式进行了包括段塞大小、段塞比以及气液体积比在内的影响因素的研究。结果表明:相对于CO2气驱、CO2水气交替驱以及CO2泡沫驱,CO2泡沫与CO2交替驱(FAG)能够解决层内矛盾,延缓气窜发生时间,扩大波及体积,提高采收率;FAG驱存在最优注入段塞大小0.4PV,最佳段塞比1:1以及最佳气液体积比1:1。
For CO2 flooding in heterogeneous reservoir,gas channeling of CO2 is easy and premature to happen along the high permeable layers,which leads to low recovery efficiency of CO2 flooding and low-permeability reservoir is difficultly produced,optimal selection of different CO2 injection modes was developed in laboratory test.The influence of slug size,foam-gas ratio and surfactant-gas ratio on the optimal injection mode was also studied.The results show that foam-gas alternative flooding is an effective practice to tackle serious interlayer contradiction and prevent early gas break-though,leading to a high oil recovery.The best parameters for FAG are as following: slug size(0.4 PV),foam-gas ratio(1∶1),surfactant-gas ratio(1∶1).