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

摘要

The ultrasonic logging is performed with dipole transducers in aluminum and luciteborehole models to study the propagation of the flexural waves in a fractured or casedborehole. The experimental results show that the flexural wave is much more sensitiveto a horizontal fracture than to a vertical one. The propagation of flexural waves ina borehole with an inclined fracture is related to both the polarization of the flexuralwave and the direction of the fracture. The experimental results show that a very stronglow-frequency flexural wave can be generated by a dipole source in a cased borehole andit propagates with the shear wave velocity of the formation. High-frequency wavesgenerated by a dipole source propagate with the compressional wave and flexural wavevelocities of the casing. Dipole acoustic well logging could be an effective means fordetermining horizontal and declined fractures and measuring the formation shear wavevelocity in a cased borehole.