Compression waves in porous media containing gas hydrate

Abstract

Wave processes in a porous medium containing water, gas and gas hydrate are numerically investigated. The two-velocity model of porous medium is used. The nonlinearity of the oscillations of the bubbles is taken into account in the equation of gas state and the equation for bubble radius. The transmission of compression of step waves from the water into hydrate-containing porous medium is investigated. Beyond the line of phase equilibrium the association of gas hydrate is possible. The influence of the medium parameters and the intensity of the incident wave on the evolution of waves in this porous medium is studied. When entering the porous medium, the initial pulse is divided into fast (deformation) and slow (filtration) waves. In a slow wave damped oscillations associated with pulsations of bubbles are observed. The increase in the initial equilibrium pressure in the medium leads to an increase in the velocities of the deformation and filtration waves. With the initial volume content of the gas in the pore space unchanged, an increase in the initial hydrate content leads to a small increase in the velocities and amplitudes of fast and slow waves. At constant initial volume content of hydrate, the increase of gas content leads to a noticeable decrease of slow wave speed and decrease of amplitudes of both fast and slow waves. It was found that the accounting of the processes of formation of gas hydrate in a porous medium at the considered time intervals does not have a noticeable effect on the character of wave propagation.