非均质油藏特高含水开发期空气泡沫驱实验研究

Experimental studies on air-foam flooding in a heterogeneous reservoir at late high water cut stage

孤岛油田在经历水驱、聚合物驱和聚驱后水驱等多轮开采后,地下剩余油高度分散,采出液含水高,开采难度加大。如何提高聚驱后油藏的采收率对于提高油田的整体开发效益尤为重要。基于"边调边驱"原则,室内开展了空气泡沫驱提高采收率方法研究。模拟了正韵律高含水油藏地质模型(由高、中、低渗并联岩心管组成)。通过对不同发泡剂质量分数、不同气液比下泡沫体系阻力因子的测定,得到最佳条件为发泡剂质量分数0.5%`和最佳气液体积比1∶1。经室内高、低采出程度下空气泡沫体系的封堵性和调驱性能实验,结果表明,优化空气泡沫的段塞组合,可大大提高不同采出程度下油藏的采收率。第一轮水驱后岩心为15.37%的低采出程度条件下,空气泡沫调驱采收率可提高22.02%;岩心采出程度高达45.53%的条件下,第二轮带有纯空气段塞的泡沫驱采收率可提高9.35%。

After oil recovery in Gudao Oil Field by water flooding,polymer flooding and subsequent water flooding,the remaining underground oil is highly decentralized,the water-cut of the producing fluid is higher,and the producing process becomes more difficult.How to enhance oil recovery of the subsequent water flooding reservoir is especially important,which can improve the overall development performance of the oil field.With the principle of profile control and oil drive,indoor research on enhancing recovery about air-foam flooding was put forth.A lab test simulated the geological model of a positive rhythmic reservoir at high water cut stage,which was composed of high/middle/low permeability parallel core.By determining the resistance factor with different mass fractions of blowing agent and different gas/liquid ratios,the best optimized results were obtained.The best mass fraction of blowing agent was 0.5%,and the best underground gas/liquid volume ratio was 1∶ 1.Indoor laboratory investigation was carried out concerning seal,profile and oil displacement characteristics under the conditions of low and high ratios of total oil produced to the original oil in place.The results showed that on the condition of low recovery percent after water drive（15.37%）,and the enhanced oil recovery（EOR） increased 22.02% by air foam flooding.After the first round air foam flooding and succeeding water flooding,the EOR was increased 9.35% by the second air foam flooding with pure air slug,and with a recovery percent of 45.53%.