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The Elastic Properties of Clay in Shales
Author(s) -
Sayers Colin M.,
Boer Lennert D.
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb015600
Subject(s) - geomechanics , anisotropy , clay minerals , geology , shear modulus , geotechnical engineering , bulk modulus , porosity , elastic modulus , stiffness , shear (geology) , mineralogy , permeability (electromagnetism) , materials science , petrology , composite material , chemistry , physics , biochemistry , quantum mechanics , membrane
The mechanical properties of clay minerals are important in many diverse scientific disciplines, including soil mechanics, civil engineering, materials science, and petroleum exploration. Rock physics provides a link between the elastic properties of rocks and their constitutive properties such as mineralogic composition, porosity, and pore‐fluid content. To accurately characterize shales, rock physics models must account for the anisotropic properties of clay minerals. Due to more compliant regions between clay particles, the elastic stiffness of clay in shales is significantly less than that of its constituent clay minerals. In this paper, the clay in shales is modeled as anisotropic clay platelets surrounded by a softer interparticle region consisting of clay‐bound water and interparticle contacts. Inverting for the elastic properties of this interparticle region indicates that its effective bulk modulus is like that of water. However, it has a nonzero effective shear modulus that is smaller by an order of magnitude, consistent with the expected shear modulus of clay‐bound water. Owing to its simplicity and robustness, it is anticipated that this model of shales, based on the properties of clay minerals and the interparticle medium, will find use in many rock physics applications, including seismic imaging, seismic inversion, and geomechanics.