摘要
低矿化度水驱作为一种经济可行、安全环保和驱油效果显著的提高采收率技术，近年来受到越来越多的关注。为进一步提高低渗砂岩油藏的水驱效果，通过表面活性剂的优选实验，提出了一种新型低矿化度活性水驱提高采收率技术，并在室内开展了岩心流动和驱油效果评价实验。岩心流动实验结果表明：在低矿化度水（2 500 mg/L）环境下，表面活性剂FHS￣101仍能表现出良好的界面活性，且活性水矿化度越低，其浸泡后的岩心薄片表面接触角越小，亲水性越强，天然岩心的渗透率损害率就越大，驱替产出液的pH值和总矿化度就越高。驱油实验结果表明：高矿化度水驱采收率为29%左右，而低矿化度水驱采收率则可以达到34%左右；高矿化度水驱后转高矿化度活性水驱的最终采收率为36.8%，而低矿化度水驱后转低矿化度活性水驱的最终采收率可以达到53.9%。这说明表面活性剂在低矿化度环境中的驱油效果更好，能够有效提高低渗砂岩油藏水驱后的采收率。
Abstract
As an economic, feasible, safe and environmental protection technology, low salinity water flooding has attracted more and more attention in recent years. In order to further improve the water flooding effect of low permeability sandstone reservoir, a new type of active water flooding technology with low salinity was put forward through the optimization experiment of surfactants, and core flow experiment and oil displacement effect evaluation experiment were carried out indoors. The results show that under the condition of low salinity water (2,500 mg/L), the surfactant FHS￣101 can still show good interfacial activity; the lower salinity of the active water results in the smaller surface contact angle of the core sheet after soaking, the stronger hydrophilicity, the greater damage rate of the permeability of the natural core, and the higher pH value and total mineralization of the displacement fluid. The oil displacement experiment results show that the oil recovery of high salinity water flooding is about 29%, while that of low salinity water flooding is about 34%; the final oil recovery of high salinity active water flooding after high salinity water flooding is 36.8%, while that of low salinity active water flooding after low salinity water flooding is 53.9%, which shows that surfactant has better oil displacement effect in low salinity environment, which can effectively improve the recovery of low permeability sandstone reservoir after water flooding.
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