Directional P-wave Remote Acoustic Imaging in an Acoustically Slow Formation

Directional P-wave remote acoustic imaging in an acoustically slow formation is discussed to improve dipole remote acoustic applications. In this paper, we start from the fundamental radiation, reflection and reception theory of a borehole dipole source. We then simulate the elastic wavefield radiation, reflection and reception generated by a borehole dipole source in an acoustically slow formation, and analyze their similarities and differences of the far-field radiation directionality of a borehole dipole-generated P-wave and monopole-generated P-wave. We demonstrate its sensitivity and feasibility in conjunction with a numerical simulation of P-wave remote acoustic imaging. The analytical results show that the dipole-generated P-wave has obvious reflection sensitivity and it can be utilized for reflection imaging and determination of the reflector azimuth. Based on the theoretical analysis above, a field example is used to demonstrate these characteristics and the application effectiveness of dipole-generated P-wave imaging and monopole-generated P-wave imaging. The results substantiate that dipole-generated P-wave has highly reflected amplitude and obvious azimuth sensitivity in an acoustically slow formation, providing an important supplement for dipole-generated S-wave remote acoustic imaging.