Consideration of Oblique Incidence in 3-D Imaging of a Planar Interface With a Circular Dipole Array in an Air-Filled Borehole
Consideration of Oblique Incidence in 3-D Imaging of a Planar Interface With a Circular Dipole Array in an Air-Filled Borehole
复制标题
DOI：
10.1109/jstars.2020.3004479
复制
发表时间：
2020-06
影响因子：
5.5
通讯作者：
S. Ebihara;Shyuhei Kotani;Kengo Fujiwara;Yuta Kimura;T. Shimomura;Ryota Uchimura
中科院分区：
文献类型：
--
作者：
S. Ebihara;Shyuhei Kotani;Kengo Fujiwara;Yuta Kimura;T. Shimomura;Ryota Uchimura
我们考虑了波的倾斜入射对阵列式定向钻孔雷达生成平面界面三维图像的影响。在本研究中，我们主要研究雷达探头靠近平面界面的情况。在这种情况下，来自平面界面的反射波可能以非常陡峭的仰角入射到接收阵列天线上。因此，井眼效应会导致波到达阵列单元的时间不同，从而在成像平面界面时会出现一些误差。通过观察到达时间的差异，我们提出了一种在生成平面界面的3-D图像时补偿这些误差的算法。计算机模拟预测，当圆形偶极子阵列天线位于岩石中充满空气的钻孔中时，可能会出现误差。数值模拟表明，我们提出的算法生成的界面在精确位置附近的三维图像，而传统方法产生的一些虚假图像与正确位置相反(即偏离位置180°)。然后，我们应用所提出的方法来分析来自岩石中真实世界断层的反射波。可以成功地创建断层的3-D图像，这是使用传统方法无法实现的。
We consider the effects of oblique incidence of a wave on the creation of a 3-D image of a planar interface with an array-type directional borehole radar. In this study, we focus on the situation where the radar probe is close to the planar interface. In such circumstances, the reflected wave from the planar interface may be incident on the receiving array antenna at very steep elevation angles. As a result, borehole effects cause differences in the arrival times of the wave at the array elements, and consequently some errors emerge in imaging the planar interface. Observing the arrival time differences, we present an algorithm to compensate those errors in creating a 3-D image of a planar interface. Computer simulations predict that the errors may occur when the circular dipole array antenna is in an air-filled borehole in rock. Numerical simulations show that our proposed algorithm generates a 3-D image of an interface around an exact position, whereas conventional methods produce some spurious images opposite to the correct position (i.e., out of position by 180°). We then applied the proposed method to analyze reflected waves from a real-world fault in rock. A 3-D image of the fault could be successfully created, which was not possible using the conventional method.