Laboratory measurements of poroelastic constants and flow parameters and some associated phenomena

In this investigation, three laboratory experiments were conducted to better characterize the coupling between fluid pressure, stress, and strain in porous rock. In the first experiment, complete sets of poroelastic constants were measured for Berea sandstone and Indiana limestone at eight different pore pressure and confining stress pairs. The Berea sandstone was most compliant at low effective stresses (drained bulk compressibility, 0.22 1/GPa; undrained bulk compressibility, 0.080 1/GPa; Skempton's B Coefficient, 0.73; and unjacketed bulk compressibility, 0.030 1/GPa at an effective stress of 3 MPa) and approached less compliant asymptotic values at higher effective stresses (drained bulk compressibility, 0.080 1/GPa; undrained bulk compressibility, 0.061 1/GPa; Skempton's B Coefficient, 0.38; and unjacketed bulk compressibility, 0.030 1/GPa at 33 MPa effective stress) whereas the poroelastic constants of Indiana limestone showed little dependence on the pore pressure and confining stress state of the sample (drained bulk compressibility, 0.048 1/GPa; undrained bulk compressibility, 0.034 1/GPa; Skempton's B Coefficient, 0.40; and unjacketed bulk compressibility, 0.0 13 1/GPa). The Berea sandstone was transversely isotropic at effective stresses less than 20 MPa and approached isotropy at higher effective stresses whereas the Indiana limestone remained isotropic at all effective stresses applied.; In the second experiment, the poroelastic coupling during a transient pore pressure test was investigated. For a positive pressure step, a small pore pressure decrease developed within the sample at early times. This induced pore pressure of opposite sign is an example of a Mandel-Cryer effect. The poroelastic response is nearly identical to the diffusive flow response after the early time interval has passed.; In the third experiment, four independent poroelastic constants (drained bulk compressibility, 0.10 1/GPa; undrained bulk compressibility, 0.021 1/GPa; Skempton's B Coefficient, 0.84; and Biot's 1/H, 0.093 1/GPa) and the hydraulic flow parameters (hydraulic conductivity, 1.3 × 10−12 m/s and specific storage, 8.6 × 10−7 l/m) were determined from a single hydrostatic loading test on Barre granite.