Numerical simulation of a borehole sidewall acoustic transmitter for single-well reflection imaging logging.

A borehole sidewall acoustic transmitter, specifically designed for openhole, introduces a unique approach to acoustic single-well reflection imaging logging, featuring transducers that directly contact the borehole's sidewall, much like the SBT tool employed in cased hole applications. Utilizing a three-dimensional finite-difference algorithm, the study conducts a numerical simulation of acoustic reflection imaging logging with the transmitter, successfully acquiring acoustic field data from both the borehole and the surrounding rock formation. Analysis of the acoustic field in rock formation shows that the radiation characteristics of the transmitter in two different work modes resemble those of tubular monopole and cross-dipole sources, respectively. Observations of an array of waveforms in the borehole suggest that the transmitter plays a crucial role in reducing the direct waves; meanwhile, the reflections also diminish, yet the ratios of their amplitudes to those of the direct waves enhance, especially for the reflected P-waves. The findings suggest that the borehole sidewall transmitter can potentially improve the effectiveness of reflected P-wave imaging logging in future applications.