页岩储层复电阻率与孔喉结构关系研究  

Relationship between complex resistivity and pore throat structurein shale reservoirs

作　　者：谭功贤 向葵[1] 严良俊[1] 罗媛元 余刚[2] TAN Gongxian;XIANG Kui;YAN Liangjun;LUO Yuanyuan;YU Gang(Key Laboratory of Exploration Technologies for Oil and Gas Resources at Yangtze University,MOE,Wuhan 430100,China;BGP,CNPC,Zhuozhou 072751,China)

机构地区：[1]油气资源与勘探技术教育部重点实验室(长江大学),湖北武汉430100 [2]中国石油集团东方地球物理勘探有限责任公司,河北涿州072751

出　　处：《石油物探》2023年第3期548-556,共9页Geophysical Prospecting For Petroleum

基　　金：国家自然科学基金面上项目(42174083,42274087);国家自然科学基金重点项目(42030805)共同资助

摘　　要：研究页岩复电阻率与孔喉结构的关系,可为页岩气储层识别及评价开辟新途径。在实验室条件下,对我国四川盆地南部探区的海相页岩样品进行了复电阻率测试,利用复合Cole-Cole模型反演电阻率和极化率,并根据毛细管束导电模型,建立极化率与平均孔喉半径、极化率与迂曲度的关系模型,实现对产气井龙马溪组储层页岩复电阻率与孔喉结构关系的研究。结果表明,页岩储层具有低阻高极化的特征,页岩的极化率与平均孔喉半径、极化率与迂曲度均具有较好的二次函数关系。研究结果进一步证实,极化率为较敏感的激电参数,与页岩气储层的孔喉结构参数关系密切,利用极化率预测和评价孔喉结构具有可行性。可根据极化率的这一特征利用复电阻率进行页岩气勘探及储层评价。Polarity is an important electrical parameter in shale reservoir evaluation that can be used to develop new methods for shale gas reservoir identification and assessment.The general model directly establishes the relationship between the resistivity and pore structural parameters.For example,Archie s formula evaluates porosity using resistivity.However,this formula has some limitations.It is an empirical formula for pure sandstone under laboratory conditions,which is unsuitable for research on shale reservoirs.However,we found that the excitation parameters(polarizability)of marine shale samples in the southern exploration area of the Sichuan Basin in China are very high;therefore,a model of the relationship between polarizability and pore throat structural parameters was established.Under the condition that shale samples are completely saturated with 40000 ppm NaCl,the complex resistivity of rock samples was measured(frequency range:0.01 Hz~10 kHz).Based on the conductivity model of the capillary tube bundle and the double Cole-Cole model,correlation models of polarizability with the average pore throat radius,polarizability,and curvature were established.The results showed that the shale reservoirs had low resistivity and high polarizability.A good quadratic function relationship existed between the polarizability and average pore throat radius,polarizability,and circuitous degree.The results confirmed that polarizability is a sensitive excitation parameter that is closely related to the pore throat structural parameters of the shale gas reservoir.Based on this characteristic of the polarizability parameters,complex resistivity parameters can be used to provide a basis for shale gas exploration and reservoir evaluation.

关 键 词：页岩 复电阻率 极化率 孔喉半径 迂曲度 

分 类 号：P631[天文地球—地质矿产勘探]