In Japan, we have many shale troubles such as, heaving, sloughing, balling, or severe effects on mud viscosity. In the report 1 to 4, the author describes following studies. 1) Suspending ability of shales in fresh water and swelling ability of clay minerals in shales. 2) Clay minerals in shales by X-ray diffraction methods. 3) Phenomenons of shales in fresh water and several electrolyte solusions. 4) Relations between phenomenons in fresh water and electrolyte solutions and clay minerals and adsorbed ions in shales.
The study was theoretically and experimentally made on the relation between vapor pressure and capillary pressure of the core. Here the discussion is stated about the method of obtaining capillary pressure curves, which can be utilized for determination of irreducible water saturation of the reservoir and of displacement pressure of the cap-rock.