饱和岩石的动态渗透率和动电耦合系数解析式  

Analytical expressions of the dynamic permeability and electrokinetic coupling coefficient in fluid-saturated rock

作　　者：时鹏 关威[1] 王军[1] SHI Peng;GUAN Wei;WANG Jun(Department of Astronautics and Mechanics,Harbin Institute of Technology,Harbin 150001,China)

机构地区：[1]哈尔滨工业大学航天科学与力学系,哈尔滨150001

出　　处：《地球物理学报》2020年第4期1695-1704,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(41874129,41574112,41674121,11734017);国家科技重大专项子课题(2017ZX05019006-006)资助.

摘　　要：动态渗透率和动电耦合系数是描述岩石中渗流波动和弹性-电磁耦合波效应的重要参数.本文基于毛细管束模型,提出了流体饱和孔隙介质的动态渗透率和动电耦合系数的解析表达式和简化表达式,并通过与前人近似式结果的对比,分析了不同表达式的合理性和适用性.在此基础上,理论分析了孔隙几何形状和孔径分布对渗透率和动电耦合系数的频率响应以及井孔震电耦合波场的影响.研究结果表明:当认为孔道均匀且达西渗透率、孔隙度和弯曲度恒定时,孔隙几何形状的影响很小,可以忽略,而前人的近似式高估了孔隙几何形状的影响;孔径分布的影响显著,随着孔径分布的增大,渗透率的临界频率显著减小,动电耦合系数的临界频率显著增加,震电测井的斯通利波及其伴随电场幅度显著增大.The dynamic permeability and Electrokinetic Coupling Coefficient(ECC)are key parameters to characterize fluid flow and coupling between elastic and electromagnetic wavefields in porous rocks.Based on the model of capillary tube bundles for porous media,we derive the analytical expressions of the dynamic permeability and the ECC.By comparing with the approximate expressions in previous studies,we examine the validity and applicability of the analytical expressions proposed in this study.Besides,we further propose the simplified expressions for the dynamic permeability and the ECC.On this basis,we theoretically analyze the influences of the pore geometry and pore-size distribution on the dynamic permeability,the ECC and the seismoelectric logging wavefields.The results show that the influence of the pore geometry is ignorable,while it is over-valuated by previous studies.The influence of the pore-size distribution is significant.With the expansion of the pore-size distribution,the critical frequency of the permeability decreases but that of the ECC increases significantly,and the amplitudes of Stoneley waves and the accompanied electric field also increase significantly.

关 键 词：动电效应 孔隙介质 动态渗透率 动电耦合系数 

分 类 号：P631[天文地球—地质矿产勘探]