缝洞型油藏溶洞储集体氮气泡沫驱注入参数及机理研究  

Mechanism and parameters of nitrogen foam flooding in cave reservoir bodies of fractured-cavity reservoirs

作　　者：屈鸣 侯吉瑞[1] 马仕希 王倩 罗旻 QU Ming;HOU Jirui;MA Shixi;WANG Qian;LUO Min(Research Institute of Enhanced Oil Recovery, China University of Petroleum-Beijing, Beij＇ing 102249, China)

机构地区：[1]中国石油大学(北京)提高采收率研究院,北京102249

出　　处：《石油科学通报》2018年第1期57-66,共10页Petroleum Science Bulletin

基　　金：国家科技重大专项"缝洞型碳酸盐岩油藏提高开发效果技术"(2016ZX05014-004-004)资助

摘　　要：溶洞是缝洞型油藏主要的储集空间,受岩溶作用影响,溶洞发育形态复杂,注水开发过程中,由于油水密度存在差异,单井上部富集大量剩余油。为研究溶洞型储集体注水开发后氮气泡沫驱不同注入参数下的驱油效果,设计制作了缝洞型油藏可视化溶洞模型进行氮气泡沫驱室内实验研究,可以直观地展示氮气泡沫驱段塞尺寸、注入时机、注采井别的变化对驱油效果影响。实验结果表明:溶洞储集体氮气泡沫驱存在最佳段塞尺寸范围,最佳段塞尺寸与溶洞发育形态、剩余油分布有关;相比转注水结束后进行氮气泡沫驱,底水驱结束后进行氮气泡沫驱可以缩短生产井高含水期,减少注水量,节约注水成本;低位井氮气泡沫驱与高位井注氮气泡沫驱剩余油分布不同,氮气泡沫与底水产生协同效应,改变水驱失效后部分溶洞中油水分布状态,提高波及体积。氮气泡沫驱提高采收率的主要机理是重力分异作用和降低油水界面张力:泡沫、油、水三相重力准数能够判断泡沫与底水协同作用的驱油效果;降低油水界面张力可使流场重新分布。室内实验研究结果可为矿场应用氮气泡沫驱开发溶洞储集体剩余油提供参考依据。Karst caves are the main storage space of fractured-cavity reservoirs. Due to karstification, the development of the caves is complicated. Because of the difference in density between oil and water, the residual oil is enriched in the upper part of single wells during water-flooding. In order to study the oil displacement effect of nitrogen foam flooding under different injection parameters after water flooding, a visual cave model of a fractured-cavity reservoir was designed and fabricated to carry out an experimental study of injection parameters of nitrogen foam flooding and visualize the oil displacement effect. The experimental results show that in terms of the cave reservoir body, there exist optimal nitrogen foam slug sizes, which vary with the characteristics of the cave and remaining oil distribution. Compared with nitrogen foam flooding after water flooding, the nitrogen foam flooding after bottom water drive could shorten the high water cut period, reduce both the water injection amount and the cost of water injection. The distribution of remaining oil after nitrogen foam flooding by a low-position well or a high-position well was different. Besides, the nitrogen foam and the bottom water could generate a synergistic effect, which changed the oil and water distribution in part of the karst cave after water flooding. The main EOR mechanism of nitrogen foam is gravity differentiation and reducing interfacial tension between oil and water. We defined a three-phase gravity criterion of foam, oil and water to describe the synergistic effect of foam and bottom water. The reduction of interfacial tension resulted in redistribution of the flow field. The results of laboratory experiments can provide reference for the development of the remaining oil in a cave body reservoir.

关 键 词：缝洞型油藏 溶洞储集体 可视化模型 氮气泡沫驱 注入参数 

分 类 号：TE357.46[石油与天然气工程—油气田开发工程]