The Effect of Pore Fluid On the Stress-dependent Elastic Wave Velocities In Sandstones Available to Purchase

Elastic wave velocities in sandstones vary with stress due to the presence of discontinuities such as grain boundaries and microcracks within the rock. The effect of any discontinuities on the elastic wave velocities can be written in terms of a second-rank and fourth-rank tensor that quantify the dependence of the elastic wave velocities on the orientation distribution and normal and shear compliances of the discontinuities. This allows the normal and shear compliance of these discontinuities to be obtained as a function of stress by inverting measurements of P- and S-wave velocities. Inversion of ultrasonic velocity measurements on dry and fluid saturated sandstones shows that the ratio of the normal to shear compliance of the discontinuities is reduced in the presence of fluid in the grain boundaries and microcracks.