Page 201 - Percolation Models for Transport in Porous Media With

Chapter 12

Effects of Acoustic Waves

on Irreversible Change of

Permeability of a Saturated

Porous Medium

Along with the electromagnetic fields, the acoustic fields are extensively used for
managing the conducting properties of reservoir rocks. Some properties of acoustic
treatment make it essentially different from electric treatment. We shall consider
the main features in the behavior of saturated porous media in an acoustic field.
The following mechanisms of interaction between the acoustic field and a satu-
rated porous medium, which cause irreversible changes in the permeability of the
latter, are possible.
1. Dissipation of the energy of a viscous Poiseuille flow in the case of mutual
displacement of the liquid and solid phases. Increase of the temperature in
the liquid results in the increase of its pressure and in the corresponding
increase of the pore channel radii, for example, because of the destruction of
the cement in the thin capillaries or on the surface of the capillaries.

2. Destruction of the surface layer of pore channels under tangential stress
generated at the interface of the solid and the viscous liquid phases during
the flow of the latter.

3. Cavitation in the pore channels as the acoustic wave passes through the
medium. The small "cumulative" jets formed when the cavitation bubbles
collapse, destroy the surfaces of pore channels and thus increase their radii.

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