随钻方位电磁波电阻率成像模拟及应用

随钻方位电磁波电阻率成像资料在地质导向中起着至关重要的作用。利用三维有限差分数值模拟方法计算随钻电阻率仪器激发的电磁场随仪器方位变化的规律，分析实现方位电阻率测量以及成像的原理及方法。数值模拟结果表明：在常规随钻电磁波仪器的基础上，增加倾斜或横向接收(发射)天线，可以实现地层方位的预测和判断，同时方位电磁波电阻率成像结果受相对井斜角、地层电导率对比以及地层地质构造的影响；利用方位电阻率成像以及定向信号成像结果可以预测和判断层界面、地层方位特征以及各向异性地层走向；幅度比电阻率成像效果优于相位差电阻率成像；在均匀各向异性介质中，线圈距和工作频率越大，视电阻率受垂向电阻率影响越大；线圈距越大，定向幅度信号越强，能预测的层界面的距离越大。

Numerical Simulation and Application of Azimuthal Propagation Resistivity Imaging While Drilling

Azimuthal propagation resistivity while drilling imaging data plays important role in geosteering. The electromagnetic field of different tool face has been simulated by three-dimensional finite difference method; the azimuthal resistivity measurement principle and imaging method is then analyzed. The numerical results show that adding tilt or transverse antenna to conventional logging while drilling (LWD) resistivity tools could get azimuth of formation. The imaging is influenced by relative deviation angles, resistivity contrast and geological structure. The imaging data can be used to forecast and determine formation boundaries, azimuth and anisotropic formation strikes. The amplitude ratio resistivity imaging is better than phase shift resistivity. In homogenous anisotropic medium, the larger coils spacing and higher frequency, the greater the influence of vertical resistivity to apparent resistivity. The bigger coil spacing, the stronger directional amplitude signals and the farther prediction distance to formation boundaries.