ИСТИНА

The importance of solving the problems of geomechanical analysis in recent years is undisputable. Main method of estimating the components of the anisotropic elastic moduli tensor is multi-element acoustic logging. The task of recovering components is complex, which leads to the use of various approximate models. Usually a model of a transversely isotropic medium is considered, which is governed by five independent components. To model their dispersion curves, the authors previously applied the semi-analytical finite element method (SAFE). However, due to the finite computational domain, one of the main difficulties is the extraction of target modes from physically unreasonable ones. To address this difficulty, the authors used zero conditions at the external boundary of the computational domain and proposed an approach for selecting physically existing borehole modes based on the analysis of their polarization, radial and spatial distributions of the kinetic energy density and the symmetry class of the eigenfunctions. In this paper, we consider and analyze the methods for improving the extraction of target borehole modes based on the introduction of radial expansion and an absorbing layer outside the main computational domain. The implementations of such layer as "Perfectly Matched Layer" (PML) and "Absorbing Layer" (AL) are considered.