Seismic Imaging of Gas Hydrate-Bearing Sediments Using Coupled Seismic and Electromagnetic Waves

Abstract

This work presents a 2D numerical model to obtain seismic images of gas hydrate bearing sediments in fluid-saturated poroelastic media. The differential model consists in Maxwell equations for the electromagnetic wave fields and Biot’s equations of motion for the seismic wave fields, coupled with a zero-order term representing electrokinetic effects. The numerical model combines the solution of Maxwell’s equation using a mixed finite element procedure using the edge-element of Nedelec with a standard Galerkin method to solve Biot’s equations of motion. Biot’s equation are discretized employing a nonconforming finite element to approximate the solid displacement and the vector part of the RaviartThomas-Nedelec space of zero order to compute the fluid displacements. The subsurface is modeled as a 2D fluid-saturated layered porous medium under transverse-magnetic (TM)modes. A numerical example illustrates the capabilities of the procedure to image gas hydrate bearing sediments in the subsurface.