Shear-wave radiation, reception, and reciprocity of a borehole dipole source: With application to modeling of shear-wave reflection survey

Abstract

The development of dipole shear-wave imaging technology requires understanding of the effects of radiation, reflection, and reception of elastic waves from a borehole dipole source, for which we provide a comprehensive analysis. We first show that the radiation of the dipole source can be accurately computed using its far-field asymptotic solution when the radiation distance is greater than wavelength. We then demonstrate the reciprocity relationship between shear-wave radiation and reception of the dipole source. Consequently, the borehole radiation pattern can be used to compute the borehole reception directivity. The use of the reciprocity relationship and the asymptotic solution greatly facilitates the modeling of the wavefield for the borehole shear-wave reflection survey. The modeling results agree well with those from a 3D finite-difference elastic wave simulation. The modeling of SH- and SV-wave radiation/reception of the dipole source also demonstrates that the SH-wave component is far greater than the SV-wave component, providing an important foundation for shear-wave reflection data processing and interpretation.