Massachusetts Institute of Technology. Earth Resources Laboratory
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