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

作　　者：JIA Hu ZHANG Rui LUO Xianbo ZHOU Zili YANG Lu 

机构地区：[1]Nation Key Laboratory of Oil and Gas Reservoir Geology and Exploitation of Southwest Petroleum University,Chengdu 610500,China [2]China Oilfield Services Ltd.,Tianjin 300459,China [3]Tianjin Branch of CNOOC Ltd.,Tianjin 300459,China

出　　处：《Petroleum Exploration and Development》2024年第2期394-402,共9页石油勘探与开发（英文版）

基　　金：Supported by the Original Exploration Project of National Natural Science Foundation of China(5215000105);Young Teachers Fund for Higher Education Institutions of Huo Yingdong Education Foundation(171043)。

摘　　要：A simulated oil viscosity prediction model is established according to the relationship between simulated oil viscosity and geometric mean value of T2spectrum,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,which agrees more with the time-varying law of reservoir wettability.

关 键 词：SANDSTONE high-multiple waterflooding nuclear magnetic resonance oil viscosity rock wettability time-varying law 

分 类 号：TE622[石油与天然气工程—油气加工工程] O657.2[理学—分析化学]