高倍数水驱砂岩中原油黏度、岩心润湿性时变规律核磁共振实验  

Nuclear magnetic resonance experiments on the time-varying law of oil viscosity and wettability in high-multiple waterflooding sandstone cores

作　　者：贾虎[1] 张瑞[1,2] 罗宪波[3] 周子力 杨璐 JIA Hu;ZHANG Rui;LUO Xianbo;ZHOU Zili;YANG Lu(Nation Key Laboratory of Oil and Gas Reservoir Geology and Exploitation of Southwest Petroleum University,Chengdu 610500,China;China Oilfield Services Ltd.,Tianjin 300459,China;Tianjin Branch of CNOOC Ltd.,Tianjin 300459,China)

机构地区：[1]西南石油大学油气藏地质及开发工程全国重点实验室,成都610500 [2]中海油田服务股份有限公司,天津300459 [3]中海石油(中国)有限公司天津分公司,天津300459

出　　处：《石油勘探与开发》2024年第2期348-355,共8页Petroleum Exploration and Development

基　　金：国家自然科学基金原创探索计划项目(5215000105);霍英东教育基金会第十七届高等院校青年教师基金(171043)。

摘　　要：根据模拟原油黏度与横向弛豫时间谱几何平均值的变化关系,建立了模拟原油黏度预测模型,并结合高倍数水驱核磁共振(NMR)实验实现了孔隙介质中模拟原油黏度的时变规律定量表征;基于核磁共振弛豫理论推导出新的NMR润湿性指数计算公式,结合砂岩岩心高倍数水驱实验,定量表征了水驱过程岩石润湿性的时变规律。研究表明:岩心中剩余油黏度与过水倍数正相关,过水倍数较低时剩余油黏度升高速度较快,过水倍数较高时剩余油黏度升高速度趋缓。剩余油黏度的变化与储层非均质性相关,储层均质性越强,剩余油中重质组分含量越高,黏度越高。注水后储层润湿性将发生改变,亲油储层向亲水储层转变,亲水储层则亲水性更强,且改变程度随过水倍数增加而增强。原油黏度的时变性与润湿性的时变性具有很高的关联性,原油的黏度变化不可忽略,考虑模拟原油黏度变化时计算得到NMR润湿性指数与测试Amott(自吸法)润湿性指数更具有一致性,更加符合储层润湿性时变规律。A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2 spectrum,and the time-varying law of simulated oil viscosity in porous media is quantitatively characterized by nuclear magnetic resonance(NMR)experiments of high multiple waterflooding.A new NMR wettability index formula is derived based on NMR relaxation theory to quantitatively characterize the time-varying law of rock wettability during waterflooding combined with high-multiple waterflooding experiment in sandstone cores.The remaining oil viscosity in the core is positively correlated with the displacing water multiple.The remaining oil viscosity increases rapidly when the displacing water multiple is low,and increases slowly when the displacing water multiple is high.The variation of remaining oil viscosity is related to the reservoir heterogeneity.The stronger the reservoir homogeneity,the higher the content of heavy components in the remaining oil and the higher the viscosity.The reservoir wettability changes after water injection:the oil-wet reservoir changes into water-wet reservoir,while the water-wet reservoir becomes more hydrophilic;the degree of change enhances with the increase of displacing water multiple.There is a high correlation between the time-varying oil viscosity and the time-varying wettability,and the change of oil viscosity cannot be ignored.The NMR wettability index calculated by considering the change of oil viscosity is more consistent with the tested Amott(spontaneous imbibition)wettability index,

关 键 词：砂岩 高倍数水驱 核磁共振 原油黏度 岩石润湿性 时变规律 

分 类 号：TE341[石油与天然气工程—油气田开发工程]