Preserved shale samples, from four different shale cores, were exposed to various fluids while under simulated downhole stress conditions. Prior to fluid exposure, the samples were not contacted by any aqueous fluid, including simulated pore fluid. Time-dependent measurements of pore pressure, swelling and acoustic velocities were made. Pore pressures both less than and greater than the applied fluid pressure were observed, and apparent osmotic membrane efficiencies are calculated. Swelling was found to depend not only on the shale type and the fluid, but also on the level of confining stress. Swelling anisotropy was observed. Acoustic velocities were found to change as a result of fluid exposure, and the amount of change is dependent on the fluid type and on the existence of swelling.

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