Method for calculation of dispersion curves, wavefields and elastic parameters of the medium in boreholes with a radially inhomogeneous alteration zone

The radial inhomogeneity of elastic properties of rock formations in the vicinity of the borehole wall, caused by drilling, tectonic stresses or other factors, considerably affects the normal mode dispersion. The current work is devoted to the study of this influence on the flexural mode dispersion curve and radial profiles of stresses and displacements fields corresponding to this mode. Besides, the method of calculation of elastic properties within the alteration zone is proposed. It is based on the analysis and inversion of waveguides dispersion curves. The proposed technique capabilities are illustrated by consideration of several models of boreholes with different types of inhomogeneity.