Electromagnetic-acoustic evaluation of the permeability of porous media

The generation of ultrasound in a porous water-saturated medium subjected t o rapid electromagnetic heating is considered. The irradiation provides the Joule heating of narrow and electrically high resistive pore throats, whic h interconnect cavities within the medium and, consequently, determine the permeability of the medium. Because of the small throat sizes, the sound ge neration is accompanied by considerable thermal flows going out from the th roats into a relatively cold environment. Due to the latter, the output of the ultrasonic measurement allows one to estimate the rate of the thermal e xchange process. A common geometric model of fluid flows and electric curre nts throughout a complicated network of intergranular cavities and their in terconnecting throats is used for calculating the permeability of a rock on the basis of the determined values of the thermal exchange rate. (C) 2001 MAIK "Nauka/Interperiodica".