Thermal and Geomechanical Dynamics of High Power Electromagnetic Heating of Rocks

Abstract

Abstract Perforation is an essential step in the cased completion of oil and gas wells, since it provides channels for hydrocarbon fluids to flow from the reservoir into production wells. Traditional methods for perforation cause plastic compaction, resulting in permeability loss in the rock around the perforation channels and reduction of the hydraulic conductivity in the surrounding rock formation. A feasible alternative is to use high power electromagnetic (HPEM) sources to induce a localized phase change in the rock via dielectric heating and create a perforation. This method has crucial benefits: it is contactless, waterless, improves conductivity, and reduces general damage to the rock formation. The physical dynamics that makes this possible have been extensively documented in several experimental studies, and some numerical models have been proposed to simulate the thermal mechanical coupling between the HPEM source and the rock for perforation and other stimulation operations. Yet, due to the inherent multi-scale complexity of the physics involved, a comprehensive model remains a topic of advanced research. Recently, a numerical scheme was proposed to predict the perforation geometry and production enhancements as a function of the HPEM source parameters (beam shape and energy distribution), rock properties, and stress configuration. This paper expands this workflow to investigate the effects of material heterogeneity and stress configuration on the perforation rate and the rock's morphology resulting from HPEM heating. The numerical model is based on a hybrid COMSOL-FLAC coupling. In a companion paper, this model is extended to describe the effect of long-pulsed thermal incidence and rock morphology using the thermal and continuum mechanic modules in FLAC.