Massachusetts Institute of Technology. Earth Resources Laboratory
Abstract
We use the ultrasonic transmission method to measure P-, SH-, and SV-wave
velocities for Chelmsford Granite, Chicopee Shale, and Berea Sandstone in different
directions up to 1000 bars confining pressure. The velocity measurements indicate
that these three rocks are elastically anisotropic. The stiffness constants, dynamic
Young's moduli, dynamic Poisson's ratios, and dynamic bulk moduli of these three
rocks were also calculated. These elastic constants, together with velocity
measurements, suggest that: (1) Elastic anisotropy is due to the combined effects of
pores/cracks and mineral grain orientation. (2) Elastic anisotropy decreases with
increasing confining pressure. The residual anisotropy at higher confining pressure is
due to mineral grain orientation
