OS02F004 Dependence of Body Wave Velocity on Borehole Stress Concentration

Abstract

In order to develop ultrasonic method for the quantitative measurement of in-situ rock stresses, we investigate the influence of stress concentration on the body-wave velocities around a borehole. First, the acoustoelasticity theory of finite-deformation solids yields a direct and explicit quantitative borehole acoustoelasticity, which reveals that the orientations of the maximum and minimum wave-velocity shifts at the borehole surface coincide with the directions of the minimum and maximum far-field principal stresses, respectively. Second, pulse-echo measurement of wave-velocity variations at the borehole surface in the sandstone sample under the biaxial compressional loadings is performed to validate the quantitative borehole acoustoelasticity. The consistence of the experimental results with the theoretical prediction means that the ultrasonic method based on acoustoelasticity theory could be a promising noncontact and non-destructive method for the quantitative measurement of in-situ rock stresses.