John R. Dennis

Acoustic well-logging transmitting and receiving transducers

An acoustic well-logging transmitting transducer employing a transmitter portion comprising stacked piezoceramic rings and a resonating metallic plate, the dimension of which determines the frequency, and a conical acoustic reflector for causing reflections to impinge omnidirectionally on the wall of the borehole at an angle to enhance shear wave component propagation. A receiving portion of similar construction can also be employed.

System for measuring shear wave travel times

A system for ascertaining with certainty that detected return acoustic cycles are shear wave cycles for the calculation of shear wave travel times using the known travel time relationship that shear wave travel times are equal to 1.55 to 1.9 times the compressional wave travel time for the same acoustic wave through most geological formations. The system determines the compressional wave travel time and determines after what point following the compression wave return that shear wave cycles are occurring. The validity of the shear wave travel time determinations using shear wave cycles after such time and that no cycles used for such measurement are skipped is assured by determining that the shear wave travel time is within the acceptable limits of 1.55 to 1.9 times the compressional wave travel time.