Field of circumferential acoustical logging devices

The circumferential acoustical device (CAD) is an acoustic logging tool for use in oil wells as a detector of vertical or near vertical fractures of the formation. Opposing pairs of acoustic transmitter and receivers are mounted in a plane perpendicular to the well axis and are pressed onto the well wall. The acoustic wave emitted by the transmitters propagates in the fluid inside the well and the formation outside the well and is received by the receivers displaced circumferentially by 90° from the transmitters. The author studies the acoustic field of the CAD by using the model of the field generated by a source in the well and close to the well wall. The calculation formulae are presented and the numerically calculated series of snapshots of the field at different time instants and the waveforms at several positions are given. The results clearly exhibit all wave components and their propagation in the field