Finite difference modeling of the acoustic field by sidewall logging devices

Sidewall acoustic logging tools have been used in oil fields for directly characterizing formations nearby boreholes and evaluating the quality of the cementation in cased holes without significant interferences of drilling mud. However so far studies on the acoustic field by such a device are only limited to a few simple cases. In this paper, we investigate the 3-D acoustic field problem with finite difference modeling for more realistic cases containing the tool body itself. We have solved the problem by employing a FDTD method with a non-uniform staggered grid. Our results demonstrate that this method can simulate such an acoustic field accurately. By comparing both the results with and without the considered tool body, we find that the existing of the logging tool body would substantially attenuate direct waves but has only little effects on interface waves.