Joint effect of capillary force and fluid distribution on acoustic signatures in rocks saturated with two immiscible fluids

Abstract

Capillary forces control the spatial distribution of pore fluids during two phase flow. Capillarity and fluid distribution are known to influence seismic signatures. By comparing recently developed capillarity-patchy saturation models for different fluid-patch distributions, we obtain an understanding of the underlying connection between capillarity and velocity and attenuation in patchy-saturated reservoir rocks. Our results show that, for the same gas saturation and patch size, P-wave velocity as well as attenuation manifest differently for various fluid distributions. The key parameter in controlling these characteristics is the specific surface area of the fluid patches. This work provides further insights into the relation between the seismic signatures and the two phase flow underpinning saturation information.