Effects of contact line movement on the dissipation of waves in partially saturated rocks

Abstract

A model is presented to describe the attenuation of seismic waves in a partially saturated rock. In particular, we include the dissipation due to contact line movement. In some cases this can dominate the dissipation mechanisms. The model includes both dissipation due to viscosity and contact line movement. This additional dissipation can increase the specific dissipation function by an order of magnitude. This could account for some of the observed difference between theory and experiment. An exact calculation of the dissipation due to contact line movement in an in viscid fluid is also presented.

Seismic attenuation in a partially saturated, artificial crack due to restricted contact line motion

“…A similar dissipation model has been proposed by Miksis [1988]. Miksis' model, however, assumes the relationship between 0 and v has no hysteresis, is strictly linear and the contact angle is always nearly 90 ø.…”

“…Miksis' model, however, assumes the relationship between 0 and v has no hysteresis, is strictly linear and the contact angle is always nearly 90 ø. A contact angle change from equilibrium is necessary to generate a force opposing contact line motion in both the Miksis [1988] and restricted meniscus motion model. The linear relationship between 0 and v in the Miksis model forces the predicted attenuation to be frequency dependent.…”

Body waves in poroelastic media saturated by two immiscible fluids

“…We should note that in these studies, although same type of governing equations were employed, the expressions for material constants differed. Miksis [1988] developed a model for wave attenuation in partially saturated rocks based on the local three-phase physics in the pore space. derived the governing equations and constitutive relations of elastic porous media saturated by two Newtonian fluids by employing the volume-averaging technique.…”

Immiscible-fluid displacement: Contact-line dynamics and the velocity-dependent capillary pressure

“…One implication of the above result is that, since the capillary-wave-generated frictional force is much larger than the viscous friction at low capillary numbers, the rigid sliding part of the ac motion can introduce additional dissipation for low-frequency waves traveling through porous media. This could be the explanation for extra dissipation observed for seismic waves in partially saturated rocks [21].…”