Shale swelling/shrinkage and water content change due to imposed suction and due to direct brine contact

摘要: Analyses were performed on nine different preserved shales, representing in situ states of 5–15 % water content and 0.13–0.42 void ratio. Under varying total suction (controlled humidity), each shale shows well-defined relationships among suction, volume change, saturation, with the lower-porosity shales undergoing less change than higher-porosity shales. A decrease porosity is also associated a much higher native state as well full saturation extending to values beyond 40 MPa. Only part high due capillary tension. direct brine exposure, almost always swell, even when has an equivalent greater shale. This likely reduction some component matric suction. The pore found equilibrate solute surrounding brine, ion diffusion. Much or all swelling, increase, appears take place clay-bound not main (free water) space. swelling magnitude consistent amount increase. Swelling usually corresponds one additional layer being added between clays. Swelling, very small for low-porosity Some osmotic effects are observable cation exchange clays takes place. best inhibited potassium, followed by sodium, calcium, brines equal activity ranging from 0.8 0.9.