Two-Phase Flow Effects on Seismic Wave Anelasticity in Anisotropic Poroelastic Media

Abstract

We study the wave anelasticity (attenuation and velocity dispersion) of a periodic set of three flat porous layers saturated by two immiscible fluids. The fluids are very dissimilar in properties, namely gas, oil, and water, and, at most, three layers are required to study the problem from a general point of view. The sequence behaves as viscoelastic and transversely isotropic (VTI) at wavelengths much longer than the spatial period. Wave propagation causes fluid flow and slow P modes, inducing anelasticity. The fluids are characterized by capillary forces and relative permeabilities, which allow for the existence of two slow modes and the presence of dissipation, respectively. The methodology to study the physics is based on a finite-element uspcaling approach to compute the complex and frequency-dependent stiffnesses of the effective VTI medium. The results of the experiments indicate that there is higher dissipation and anisotropy compared to the widely used model based on an effective fluid that ignores the effects of surface tension (capillarity) and viscous flow interference between the two fluid phases.

Prediction of dispersion and attenuation on elastic wave velocities in partially saturated rock based on the fluid distribution obtained from three-dimensional (3D) micro-CT images

“…The third step is the oscillatory relaxation test (e.g., Rubino et al, 2009;Chapman and Quintal, 2018;Santos et al, 2021).…”

“…Another way to predict the effect of mesoscopic flow on dispersion/attenuation is to use numerical models. It usually takes the fluid distribution as an input, and uses the finite element method to obtain the solution (e.g., Santos et al, 2005;Rubino et al, 2009;Quintal et al, 2011;Santos et al, 2021). The numerical model is computationally expensive compared to the analytical model.…”

Advances in Multifield and Multiscale Coupling of Rock Engineering

“…The seepage increases the sliding force of the perilous rock and aggravates the opening of cracks at any time. (3) The stability of the surface perilous rock mass is largely affected by the mining of underground coal mines. The simulation analysis was repeated using the method of setting coal pillars.…”

“…These findings provide important theoretical support for the tectonic coal deformation law and action mechanism in the damage process that occurs under complex stress conditions. Santos et al [3] studied the wave anelasticity (attenuation and velocity dispersion) of a periodic set of three flat porous layers saturated by two immiscible fluids. The fluids are very dissimilar in regard to properties, namely gas, oil, and water, and, at most, three layers are required to study the problem from a general point of view.…”

Scholte Wave Field and Dispersion Curve in Porous Multi-layered Media Filled with Fluid

“…Ali (1993) established a semi-infinite elastic seabed model with sedimentary layers, simulated and analyzed the influences of seabed sediments on the dispersion characteristics of Scholte wave. The results show that the soft sedimentary layers covered on a hard seabed has the greatest effect on the dispersion curves of Scholte wave, and the high frequency components attenuate greatly in the sedimentary layers (Pfeffer and Zarichny, 1963;Chamuel, 1998;Dahm and Grevemeyer, 2009;Manuel et al, 2013;Santos et al, 2021;). In dispersion theory, Pham (2013) used the complex function method to derive the dispersion equation of Scholte wave for the semi-infinite space, and proved that Scholte wave is unique (Billy and Quentin, 1990;Souza and Ulson, 2003;Wilken et al, 2009;Zhu et al, 2016;Krylov et al, 2022b).…”