Wettability effect on wave propagation in saturated porous medium

Abstract

Micro-fluid mechanics studies have revealed that fluid slip on the boundary of a flow channel is a quite common phenomenon. In the context of a fluid-saturated porous medium, this implies that the fluid slippage increases with the increase of the hydrophobicity, which is the non-wetting degree. Previous studies find that wettability of the pore surface is strongly related to the slippage, which is characterized by slip length. To accurately predict acoustical properties of a fluid-saturated porous medium for different wettability conditions, the slippage of the wave-induced flow has to be taken into account. This paper introduces the slip length as a proxy for wettability into the calculation of the viscous correction factor, dynamic permeability, and dynamic tortuosity of the Biot theory for elastic waves in a porous medium. It demonstrates that, under different wettability conditions, elastic waves in a saturated porous medium have different phase velocity and attenuation. Specifically, it finds that increasing hydrophobicity yields a higher phase velocity and attenuation peak in a high-frequency range.