Anisotropy In A Vicinity Of A Borehole From The Qp Wave Slowness And Polarization

We propose an algorithm for evaluating weak anisotropy parameters at receivers in a borehole in a multi-<br>azimuthal multiple-source o set VSP experiment. The parameters can be determined from measurements of<br>slowness vectors and/or deviations of measured qP wave particle motions from the slowness vectors at indi-<br>vidual receivers. The formulae presented are applicable under assumption of arbitrary but weak anisotropy<br>and vertical inhomogeneity of the medium. The formulae represent, in several respects, generalization of an<br>algorithm proposed by Gaiser (1990) and an alternative to the algorithm proposed by Horne et al. (1998).<br>Basic formulae and a synthetic example of their application are presented.