Aquecimento eletromagnético aplicado à recuperação avançada de óleo e ao armazenamento de energia limpa

Abstract

Water-flooding aided by electromagnetic heating using microwaves has a great potential for heavy oil recovery. The radiant energy is absorbed by water and converted into heat near the EM source. The heat is imparted into the oil phase while being transported deep into the porous medium. Under this premise, a model was developed. The model is solved numerically using a staggered algorithm joining Galerkin Least Square Finite Elements Method and Kurganov-Tadmor Finite Volumes Method. Numerical results were obtained for different types of oil. For the considered parameter values, the eletromagnetic heating technique increments the oil production up to 56% after a 24-month injection. This increment is inversely proportional to the oils API gravity (directly proportional to viscosity). The implementation was validated by comparing computational results with the simplified model’s analytical solution obtained using Conservation Laws theory and the Sturm-Liouville theory. Simple convergence analysis was also performed endorsing our numerical approach. Analytical and numerical approaches were obtained for the two-dimensional geometry with two parallel horizontal wells. The temperature profile obtained through the simplified model’s analytical solution is close to the one obtained by simulations (less than 1.9% relative error). On the other hand, the water-flooding aided by electromagnetic heating is an emerging method for storing renewable energy, such as photovoltaic solar and wind electric power, into aquifers. We investigate how the captured energy increases the temperature of a prototypical deep aquifer for six month period and then to which extent the stored energy can be recovered during the consecutive six months. Water injected at a constant flow rate is simultaneously heated using a high-frequency electromagnetic microwave emitter operating at the water natural resonance frequency 2.45 GHz. The coupled reservoir flow and heating are described using Darcy’s and the energy balance equations. The latter includes a source term accounting for the wave propagation and absorption, modeled separately using Maxwell’s equations. The equations are solved numerically by the Galerkin Least square finite elements method. The approach was validated using EM-heating input data obtained from controlled laboratory experiments and then was applied to the aquifer. We found that, after six years of alternate storage and recovery, up to 77% of the injected energy is recovered when considering realistic heat losses estimated from field data. Even when heat losses are increased by a factor of two, up to 69% of the injected energy is recovered in this case. This shows that down-hole eletromagnetic heating is a highly effective method for storing renewable energies, capable of helping to solve their inherent intermittency.