水平电流环激发的井外孔隙地层SH波模拟

Simulation of the SH wave excited by a horizontal current loop centered in a borehole surrounded by a porous formation

通过求解完整的Pride声电耦合波方程组,并利用井壁处流体-孔隙介质交界面的场量连续性条件,推导出位于井轴的水平电流环激发的井内外电磁场和声场的解析表达式,模拟了水平电流环激发的电-声转换测井全波。由于水平电流环激发的TE波在孔隙地层中只与SH波耦合,诱导声波按地层横波速度传播,使得利用水平电流环激发的电-声测井在地层横波速度测量方面具有潜在的应用价值。

Analytical expressions of the electroseismic wavefields excited by a horizontal current loop centered in a fluid-filled borehole surrounded by a porous formation are derived by solving Pride＇s electrokinetic coupling equations and using the continuity condition on the borehole wall.Full waveforms of the electroseismic logging excited by the horizontal current loop are simulated.In porous formations the transverse electric（TE） field excited by a horizontal current loop is coupled only with the shear horizontal（SH） wave,thus such electroseismic logs have potential value in measuring shear wave velocity of formations.