Stress-Induced Anisotropic Poroelasticity Response in Sandstone.

摘要

We present measurements of the elastic and poroelastic (both drained and undrained) properties of intact Berea sandstone at confining pressures up to 50 MPa and differential stresses from 0 to 120 MPa. Tests were carried out under axisymmetric loading conditions so that the rock developed transverse anisotropy as stress was applied. We measured the drained and undrained Young's moduli and Poisson's ratios in axial (z) and transverse (t) directions over the entire range of confining pressure and differential stress. We also directly measured the isotropic Skempton coefficient , as well as axial and transverse 'generalized' Skempton coefficients. t In addition we directly determined the pore space storage coefficient. The sandstone has intrinsic anisotropy at low confining pressure and stress-induced anisotropy which increases with applied differential stress due to reversible changes in pore structure.