Advanced one-dimensional modeling of thermite reaction for thermal plug and abandonment of oil wells

Resumo

© 2023 Elsevier LtdThis paper presents an improved one-dimensional nonstationary model to simulate the reaction propagation of aluminum and iron-oxide in thermite mixtures. This model is motivated by the application of thermite mixtures for thermal plug and abandonment of oil wells. The main improvements of this model include the chemical source term correction in the energy conservation equation, and the imposition of a temperature limit to account for aluminum vaporization. A simplified, first-order, one-step mechanism governed by the Arrhenius relation was assumed, and different pairs of activation energy and pre-exponential factor were analyzed, including some pairs that reproduce the experimental propagation speed reported in the literature. Numerical simulations were done to generate contour plots that map the effects of the kinetics parameters, alumina dilution, and aluminum addition to the initial mixture in the main characteristics of the reaction wave, such as velocity, thickness, ignition delay, and initiation temperature. These simulations indicate that, at alumina dilution of 20% or more, the simulated thermite reaction does not reach the aluminum vaporization temperature and may not present disruption of the system. The model shows that aluminum addition to the initial mixture accelerates the propagation and the numerical results reproduces experimental data from literature. Also, below a burning velocity of 26 mm/s and alumina-dilution higher than 40%, the reaction does not self-propagate.

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