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