特低渗油藏CO_(2)/水交替微观驱油机理研究  

Microcosmic oil displacement mechanism of CO_(2)/water alternation in ultra-low permeability reservoirs

作　　者：梁珀 LIANG Po(China Petroleum and Chemical Corporation East China Oil and Gas Branch,Nanjing 210019,China)

机构地区：[1]中国石油化工股份有限公司华东油气分公司,江苏南京210019

出　　处：《断块油气田》2024年第4期746-752,共7页Fault-Block Oil & Gas Field

基　　金：江苏省项目“苏北地区二十万吨级CCUS重大科技示范工程”(BE2022603)。

摘　　要：苏北盆地断块特低渗透油藏具有“小、碎、深、薄、低”的典型特征,在经过短期弹性开发后如何优选合理高效的提高油藏采收率方法成为该类油藏面临的瓶颈问题。水气交替注入(Water Alternating Gas,WAG)方法能有效抑制水窜和气窜,兼具水驱和CO_(2)驱的优点,在特低渗透油藏取得了成功应用,但其微观驱油机理及实际效果仍需进一步研究和评价。文中以苏北ZD油田为研究对象,基于特低渗透天然岩心的三维数字模型,应用孔隙尺度微观数值模拟方法,研究了CO_(2)/水交替驱油过程中气水相界面的动态演化过程,并深入阐明了特低渗油藏WAG提高采收率的微观机理,结果表明:水气交替驱具有更大的波及面积和更少的剩余油体积,CO_(2)驱过程具有更好的流动性和克服黏滞力的能力,同时水驱过程中的渗吸作用和封堵作用能有效提高驱油效率。因此,CO_(2)/水交替驱可以有效启动特低渗储层,起到调剖调驱协同增益的作用,研究成果对于指导特低渗透油藏提高采收率技术的优选和实施具有重要的理论意义和矿场应用价值。Low-permeability fault reservoirs in northern Jiangsu Basin are characterized by small,fragmented,deep,thin,and low-permeability formations,posing challenges in selecting efficient methods to enhance oil recovery after short-term elastic development.The Water Alternating Gas(WAG)method,with its ability to suppress water and gas channeling,has been successfully applied in low-permeability reservoirs by combining the advantages of water and CO_(2)flooding,but its microscale oil displacement mechanism and practical effects still need further research and evaluation.In this study,taking the ZD oilfield in northern Jianngsu Basin as the research object,a pore-scale microscopic numerical simulation method based on the three-dimensional numerical model of ultra-low permeability natural core was used to investigate the dynamic evolution of gas-water interfaces during CO_(2)/water alternating flooding and to elucidate the microscopic mechanism of improved oil recovery in low-permeability reservoirs with WAG.The results showed that the WAG method resulted in larger swept areas and less residual oil volume.CO_(2)flooding exhibited better flowability and ability to overcome viscosity effects,while water flooding demonstrated enhanced oil displacement efficiency through imbibition and plugging.Therefore,WAG can effectively stimulate low-permeability reservoirs and synergistically enhance oil recovery by improving reservoir sweep and displacement efficiency.The findings of this study have important theoretical significance and practical field value for guiding the selection and implementation of oil recovery techniques in low-permeability reservoirs.

关 键 词：特低渗油藏 CO_(2)/水交替驱 数字岩心 孔隙尺度模拟 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]