Effective wave dispersion and attenuation in three-periodic thin poroelastic layers saturated by two-phase fluids

Abstract

Wave induced fluid flow (WIFF) in fluid-saturated poroelastic media occurs due to conversion of fast to slow diffusion P-waves at mesoscopic scales, which are much larger than the average pore size and much smaller than the traveling fast Pwave wavelengths. In this work we show that in hydrocarbon reservoirs, where the pore space is saturated by two-phase fluids, capillary pressure and interference betweeen the fluid of the two phases induce additional velocity attenuation and dispersion of seismic waves. We present a Finite Element (FE) procedure to determine the phase velocities and dissipation factors in a three-periodic fine layered poroelastic medium saturated by two-phase fluids. Firstly, the numerical results are compared with those of single-phase effective fluids and then, cases of patchy saturation are analyzed. The results show that residual saturations and wettability influence the effective Pwave phase velocities and dissipation factors.