Reciprocity in the radiation and reception of shear waves from a borehole dipole source and its application to fast simulation of shear-wave reflection survey

Abstract

Summary Realistic simulation of waveform data from a borehole acoustic reflection survey needs to model the effects of radiation, reflection, and reception of elastic waves from a borehole source, which usually requires extensive effort in the modeling. Using elastic reciprocity theorem and numerical modeling, we show that the shear-wave radiation from a borehole dipole source is reciprocal to the reception in the source orientation, of the borehole fluid displacement caused by the incidence of plane shear waves upon the borehole. Consequently, the borehole radiation pattern can be utilized to compute the borehole reception directivity. Furthermore, the radiation away from borehole can be accurately computed using a far-field asymptotic solution. The use of the reciprocity theorem and the asymptotic solution greatly reduces the computational effort in the reflection survey simulation. The simulation results agree well with those from a 3D finite difference elastic wave simulation. The result of this work provides a fast algorithm for simulating the dipole-shear wave reflection survey along a borehole.