Experimental Study Of The Flexural Waves In The Fractured Or Cased Borehole Model

Abstract

The ultrasonic logging is performed with dipole transducers in aluminum and lucite borehole models to study the propagation of the flexural waves in a fractured or cased borehole. The experimental results show that the flexural wave is much more sensitive to a horizontal fracture than to a vertical one. The propagation of flexural waves in a borehole with an inclined fracture is related to both the polarization of the flexural wave and the direction of the fracture. The experimental results show that a very strong low-frequency flexural wave can be generated by a dipole source in a cased borehole and it propagates with the shear wave velocity of the formation. High-frequency waves generated by a dipole source propagate with the compressional wave and flexural wave velocities of the casing. Dipole acoustic well logging could be an effective means for determining horizontal and declined fractures and measuring the formation shear wave velocity in a cased borehole.Massachusetts Institute of Technology. Borehole Acoustics and Logging ConsortiumUnited States. Dept. of Energy (Grant DE-FG02-86ER13636