Aspects of Thermal Fracturing of Clays with Electromagnetic Excitation

Abstract

The study explores the feasibility of fracturing clays during fast electromagnetic (EM) heating. An oedometer setup customized with an EM wave source is simulated numerically at the continuum level. Solid matrix equilibrium, fluid flow and heat transfer equations are solved together with the laws of electromagnetism, i.e. Maxwell’s equations, using the COMSOL multiphysics code. Numerical simulations involve EM excitation in a fluid-saturated isotropic, homogeneous, linear thermo-poro-elastic and lossy (EM wave loses power as it propagates in a lossy material.) medium at both 50 MHz and 2.45 GHz frequencies. It is found that the thermal expansion contrast between the fluid and solid phase results into a local buildup of fluid pressure that cannot dissipate due to the very low permeability of the medium, hence promoting fracturing.