页岩各向异性的全光学检测

Non-contact measurement of the anisotropy in shale with all-optical detection

本文利用全光学方法对不同地区的页岩样本进行各向异性检测.利用激光在页岩等岩石中激发产生超声波,基于激光干涉原理对超声波速进行检测,从而获得页岩层理结构的各向异性分布特点.检测结果表明超声纵波波速与页岩层理结构吻合得很好.超声纵波沿页岩层理面传播时速度最大,垂直页岩层理面传播时速度最小,超声波速关于页岩层理方向以正弦规律对称分布.不同地区的页岩超声波速也不同.全光学检测方法可以实现对页岩层理结构的快速判断,根据在页岩中传播的超声波速可了解页岩的致密度及各向异性强度,对页岩储层的开发具有一定指导意义.

The method of all-optical detection was used to investigate the anisotropy in shale samples from different regions. The ultrasonic wave was excited in shales by pulsed laser and detected by optical interferometry. The anisotropic distribution characteristics of the shales were studied by gaining the ultrasonic wave velocity. The results show that ultrasonic P-wave velocity periodically changed with the angle between the detection direction and the bedding in shale. The P-wave velocity reached its maximum when the angle was zero, that the detection direction parallel to the bedding. And the P-wave velocity reached its minimum when the angle was right, that the detection direction perpendicular to the bedding. The all-optical detection method provide a way to rapidly judge the bedding direction in shale or in other rocks, which give guidance for the development on the shale reservoir.