Capillary forces in the acoustics of patchy-saturated porous media.
A linearized theory of the acoustics of porous elastic formations, such as rocks, saturated with two different viscous fluids is generalized to take into account a pressure discontinuity across the fluid boundaries. The latter can arise due to the surface tension of the membrane separating the fluids. We show that the frequency-dependent bulk modulus K(omega) for wavelengths longer than the characteristic structural dimensions of the fluid patches has a similar analytic behavior to the case of a vanishing membrane stiffness and depends on the same parameters of the fluid-distribution topology. The effect of the capillary stiffness can be accounted for by renormalizing the coefficients of the leading terms in the low-frequency limit of K(omega).
Tserkovnyak
Yaroslav
Y
Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138, USA. yaroslav@physics.harvard.edu
Johnson
David Linton
DL
D000162:Acoustics; D004548:Elasticity; D008962:Models, Theoretical; D016062:Porosity; D014783:Viscosity