| 声电效应测井的有限差分模拟 |
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| 引用本文： | 关威,姚泽鑫,胡恒山.声电效应测井的有限差分模拟[J].地球物理学报,2017,60(11):4516-4526. |
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| 作者姓名： | 关威 姚泽鑫 胡恒山 |
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| 作者单位： | 哈尔滨工业大学航天科学与力学系, 哈尔滨 150001 |
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| 基金项目： | 国家自然科学基金项目（41574112，11372091，41674121）和黑龙江省自然基金项目（D2015001）联合资助. |
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| 摘 要： | 本文研究声电效应测井波场的有限差分模拟算法.忽略井外地层中诱导电磁场对孔隙弹性波的影响,将求解动电耦合波方程组的问题解耦,先计算孔隙弹性波,再计算其诱导电磁场.基于轴对称柱坐标系下的速度-应力交错网格,采用时域有限差分计算井孔流体声波和井外地层孔隙弹性波.将电磁场近似看作似稳场,基于轴对称柱坐标系下的5点式有限差分网格,求解不同时刻的电位Poisson方程,计算诱导电场.结果表明:本文算法可准确模拟频率6.0 kHz的声电效应测井全波;在声波测井频率范围内,电导率、动电耦合系数和动态渗透率的低频近似对伴随电磁场的计算影响不大;地层水平界面导致伴随反射斯通利波的电场和显著的界面电磁波,后者对于探测地层界面具有潜在的应用价值.
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| 关 键 词： | 动电效应 测井 有限差分 孔隙介质 动电电磁场 |
| 收稿时间： | 2017-02-09 |
Finite-difference modeling of seismoelectric logs |
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| GUAN Wei,YAO Ze-Xin,HU Heng-Shan.Finite-difference modeling of seismoelectric logs[J].Chinese Journal of Geophysics,2017,60(11):4516-4526. |
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| Authors: | GUAN Wei YAO Ze-Xin HU Heng-Shan |
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| Institution: | Department of Astronautics and Mechanics, Harbin Institute of Technology, Harbin 150001, China |
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| Abstract: | In this study, a finite-difference algorithm is proposed for simulating the seismoelectric logs. Without the negligible feedback effect of the Electromagnetic (EM) field on poroelastic waves, the equations for the electrokinetic coupling waves in a fluid-saturated porous medium are solved by two steps. The poroelastic wave is calculated first and then the EM field is calculated. The acoustic waves in the borehole and the poroelastic waves in strata are computed by using the finite-difference time-domain method with a velocity-stress staggered grid in axisymmetric cylindrical coordinates. The EM field is considered as a quasi-static field and obtained by using the finite-difference method with five-point formula to solve the Poisson equation for electric potential. The results show that the presented algorithm can simulate the seismoelectric logs accurately when the source frequency is lower than 6.0 kHz. Within the whole frequency range of logging, the low-frequency limit approximations of the conductivity, electrokinetic coupling coefficient and dynamic permeability do not influence the results significantly. The horizontal interfaces cause an electric field accompanying reflected Stoneley waves and significant interface EM waves. The latter has a potential application in exploring stratum interfaces nearby boreholes. |
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| Keywords: | Electrokinetic coupling Logging Finite-difference Porous medium Seismoelectric field |
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