Abstract

P- and S-wave velocities have been measured on six sandstone samples with different porosities and permeabilities under hydrostatic confining stresses to 60 MPa, while maintaining the pore pressure at 1 atmosphere. In addition, the air permeability of these sandstones in their dry condition and their electrical conductivity in the brine-saturated state have been measured under the same confining stresses at the same time as the velocity measurements. The theory of Toksoz et al. (1976) is employed to model velocity data. The fluid flow model of Walsh and Brace (1984) has been used to model the transport properties of the rock as a function of confining stress. In the latter case, the change in half crack aperture determined from permeability and electrical conductivity is related to the change in crack porosity which, in turn, can be obtained from the theory of Toksoz et al. (1976). It is found that the relationship between the two parameters is linear, with a slope representing the pore surface area per unit bulk volume of the rock. The results have been compared with those obtained from scanning electron microscope (SEM) photographs and reasonable agreement has been observed.