Wave simulation in frozen porous media

We propose a numerical algorithm fur simulation of wave propagation in froz en porous media. where the pore space: is filed with ice and water. The mod el, based on a Riot-type three-phase theory. predicts three compressional w aves and two shear waves and models the attenuation level observed in rocks . Attenuation is modeled with exponential relaxation functions which allow a differential formulation based on memory variables. The wavefield is obta ined using a grid method based on the Fourier differential operator and a R unge-Kutta time-integration algorithm. Since the presence of slow quasistat ic modes makes the differential equations stiff, a time-splitting integrati on algorithm is used to solve the stiff part analytically. The modeling is second-order accurate in the lime discretization and has spectral accuracy in the calculation of the spatial derivatives. (C) 2001 Academic Press.