Wave velocities in rocks as a function of change in overburden pressure and pore fluid saturants

Abstract

Abstract A system is described for determining precisely the dilatational and shear-wave group velocities in rock samples subjected to hydrostatic confining and internal pore pressures independently to 10,000 psi. Both velocities have been measured on three dry sandstones in directions perpendicular and parallel to the bedding plane. Two exhibited transverse isotropy with the bedding plane as the plane of symmetry, decreasing in degree as confining pressure increased. If effects of mechanical hysteresis of the rock were avoided, the velocities in sandstones depended on the simple difference between the hydrostatic confining pressure and internal pore pressure.