Importance of anisotropy when estimating and measuring in situ stresses in rock

Damage-induced permeability changes in granite: a case example at the URL in Canada

Directionally dependent attenuation in transversely isotropic (TI) media can influence significantly the body-wave amplitudes and distort the results of the AVO (amplitude variation with offset) analysis. Here, we develop a consistent analytic treatment of plane-wave properties for TI media with attenuation anisotropy. We use the concept of homogeneous wave propagation, assuming that in weakly attenuative media the real and imaginary parts of the wave vector are parallel to one another. The anisotropic quality factor can be described by matrix elements Qij , defined as the ratios of the real and imaginary parts of the corresponding stiffness coefficients. To characterize TI attenuation, we follow the idea of the Thomsen notation for velocity anisotropy and replace the components Qij by two reference isotropic quantities and

Plane-wave propagation in attenuative transversely isotropic media

Crustal stress determination from boreholes and rock cores: Fundamental principles

The correlations between the saturated and dry P-wave velocity of rocks.

Experimental ultrasonic velocities and permeability for sandstones with aligned cracks

Shear-wave velocity and Q anisotropy in rocks: A laboratory study

Stress-induced ultrasonic wave velocity anisotropy in a sandstone

Abstract A polyaxial (true triaxial) stress-loading system has been developed for testing cubic specimens of rock, with the capability of varying each of the principal stresses independently. Facilities are incorporated for measuring all nine components of P and polarized S-wave velocities and attenuation in the principal directions, and for fluid permeability in the 1-direction. Tests have been performed on specimens of five sandstones, in which systems of aligned cracks have been introduced by increasing σ1 and σ2 together to near failure, while maintaining σ3 constant at some low level. Results indicate that there are excellent correlations between permeability in the plane of the aligned cracks as they are closed under hydrostatic stress and both velocities and attenuation of (1) P and S waves propagating in a direction normal to the plane of the cracks, and (2) S waves propagating in the plane of the cracks and polarized normal to the plane.

Acoustic wave propagation and permeability in sandstones with systems of aligned cracks

Velocity anisotropy of carboniferous mudstones

M.S. King

Papers

Experimental ultrasonic velocities and permeability for sandstones with aligned cracks

Shear-wave velocity and Q anisotropy in rocks: A laboratory study

Stress-induced ultrasonic wave velocity anisotropy in a sandstone

Acoustic wave propagation and permeability in sandstones with systems of aligned cracks

Velocity anisotropy of carboniferous mudstones