Experience in applying the acoustopolarization method fpr metamorphosed rock samples from Kola (SG-3), German (KTB-HB) and Finnish (OKU) investigation boreholes

Abstract

The paper presents the use of the acoustopolarization method for the study of elastic-anisotropic properties of the rock samples from the Kola (SG-3), German (КТВ-НВ) and Outokumpu (OKU) boreholes. Investigations showed that using this method one can reveal elastic anisotropy, evaluate the heterogeneity of rock samples and determine orientation of the elastic symmetry elements. It is possible to determine the type of the rock elastic symmetry without defining 3D distribution for compression and shear waves. In the rock samples from SG-3, КТВ-НВ and OKU the linear acoustic anisotropic absorption (LAAA) is rather common. The results obtained can be used for better interpretation of the palaeodynamic studies of formation conditions of metamorphic rocks. ARTICLE INFO

Static and dynamic pressure sensitivity anisotropy of a calcareous shale

“…It has been long known that the physical properties of most rocks depend nonlinearly on confining stress with this behaviour attributed to the progressive closure of compressible crack‐like pores. A corollary manifestation of this nonlinearity is that application of deviatoric stress states induces anisotropy, a topic that has generated a great deal of interest and many literature works in the seismological community based on studies in the laboratory (e.g., Nur and Simmons () and Gorbatsevich and Kovalevskiy ()), theoretical analyses (e.g., Sayers and Kachanov (); Johnson and Rasolofosaon (); and Collet et al . ()), and in the field (e.g., Crampin (); Oda, Yamabe, and Kamemura (); Schijns et al .…”

“…It has been long known that the physical properties of most rocks depend nonlinearly on confining stress with this behaviour attributed to the progressive closure of compressible crack-like pores. A corollary manifestation of this nonlinearity is that application of deviatoric stress states induces anisotropy, a topic that has generated a great deal of interest and many literature works in the seismological community based on studies in the laboratory (e.g., Nur and Simmons (1969) and Gorbatsevich and Kovalevskiy (2015)), theoretical analyses (e.g., Sayers and Kachanov (1995); Johnson and Rasolofosaon (1996); and Collet et al (2014)), and in the field (e.g., Crampin (1981); Oda, Yamabe, and Kamemura (1986); Schijns et al (2012); and Shelley et al (2014)). This effect is particularly interesting around a vertical borehole drilled through a formation subject to differing maximum and minimum horizontal compressions S H and S h , respectively, as their concentration around the borehole results produces a cyclical pattern of opening and closing of microcracks around the borehole, as illustrated in Fig.…”