When a poro-elastic beam is suddenly bent, pressure is imposed on the liquid in the pores, so it begins to flow. This leads to a decrease in the amount of force needed to sustain the deflection of the beam. The time that it takes for the pressure in the pores to be released is related to the permeability of the beam, so a measurement of the force on the beam can be used to measure permeability. This technique has been used extensively in the Scherer lab for a variety of materials, including gels, porous glass, cement, and stone.
Post-doctoral researcher Jie Zhang has made an extensive series of measurements on shales supplied by Rusty Riese (BP) from cores obtained at several sites. The permeabilities range from less than 1 to more than 100 nanodarcies. The data show reasonable agreement with the Katz-Thomson equation, which relates permeability to pore size.