黔东页岩复电阻率各向异性及其与页岩气储层参数关系研究  

Anisotropy of complex resistivity of the shale in eastern Guizhou province and its correlations to reservoir parameters of shale gas

作　　者：成联正[1,3] 王赟 张川[1] CHENG LianZheng;WANG Yun;ZHANG Chuan(State Key Laboratory of Ore Deposit Geochemistry,Institute of Geochemistry,Chinese Academy of Sciences,Guiyang 550081,China;School of Geophysics and Information Technology,China University of Geosciences(Beijing),Beijing 100083,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室,贵阳550081 [2]中国地质大学(北京)地球物理与信息技术学院,北京100083 [3]中国科学院大学,北京100049

出　　处：《地球物理学报》2021年第9期3344-3357,共14页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41425017);国家重点研发计划项目(2016YFC0600301,2017YFC0602500)联合资助.

摘　　要：电法勘探因其成本低、效率高的优势,常被作为寻找页岩气储层的辅助手段.然而,到目前为止,页岩的电性特征,特别是复电阻率各向异性特征,以及其与页岩气储层参数的关系研究甚少,这在一定程度上阻碍了电法勘探在页岩气勘探中的应用.基于此,本文采集了黔东地区几种典型黑色页岩岩样,并测量了6块黑色页岩在走向、倾向和垂直层理方向的复电阻率,分析了其各向异性特性,讨论了电阻率与总有机碳(TOC)含量、脆性矿物含量、最大镜质组反射率等页岩气储层参数之间的关系.研究表明:(1)页岩复电阻率振幅各向异性存在频率依赖的特征,在中低频阶段,页岩复电阻率振幅各向异性明显,垂直层理方向复电阻率振幅显著大于走向、倾向方向复电阻率振幅,但随频率增加,页岩复电阻率振幅各向异性差异减小,甚至趋于各向同性;(2)复Cole-Cole模型能很好地拟合页岩三方向的复电阻率数据;(3)走向、倾向方向电阻率与TOC含量存在显著的线性正相关关系,通过走向、倾向方向电阻率预测TOC含量有一定可行性;(4)电阻率与脆性矿物含量、黏土矿物含量、最大镜质组反射率关系复杂,未发现简单的线性相关关系.上述研究结果对我们全面了解黔东地区黑色页岩的电性特征,促进电法勘探在页岩气勘探中的应用大有裨益.The electrical method is widely used to recognize the best shale reservoirs due to its low cost and high efficiency compared with the seismic method.However,there are a few studies about the electrical properties of shale,especially the anisotropy of complex resistivity and its correlations to parameters of shale gas reservoirs,which limits the application of the electrical method in shale gas exploration.In this paper,we discuss the anisotropic properties of complex resistivity in 3 orthogonal directions and the relationships between resistivity and reservoir parameters of shale gas such as Total Organic Carbon(TOC)content,brittle minerals content and maximum vitrinite reflectance.All discussions are based on the experimental data obtained through analyzing six typical shale samples collected from eastern Guizhou Province.Research suggests that:(1)The anisotropy of amplitudes of complex resistivity varies with the frequency.In low and medium frequency bands,the vertical amplitude of complex resistivity is significantly greater than the strike and dip ones.However,with the increasing of frequency,the differences of amplitude among 3 orthogonal directions become smaller.Even at a certain frequency,the anisotropy of amplitude disappears.(2)The double Cole-Cole model fits well with the measured complex resistivity data of shale.(3)The TOC content has significant linear positive correlations with the strike resistivity and dip resistivity.Thus,it is possible to predict TOC content through the strike or dip resistivity.(4)No evident relationships are found between the resistivity,brittle mineral content and maximum vitrinite reflectance.The reason is the complexity of the influence of brittle minerals content and vitrinite reflectance on resistivity.The presented research results are beneficial to gain a comprehensive understanding of the electrical characteristics of shale and provide a new way to evaluate shale gas reservoirs.

关 键 词：页岩 各向异性 复电阻率 总有机碳 脆性矿物 镜质组反射率 

分 类 号：P631[天文地球—地质矿产勘探]