Thermal behavior of aluminothermic thermite reaction for application in thermal sealing of oil wells

Abstract

Motivated by a groundbreaking proposal to plug depleted oil wells using an exothermic reaction to melt the wellbore components, this work investigates the thermal behavior associated with the longitudinal propagation of a stoichiometric Fe2O3/Al thermite reaction. The primary objective of this study is to develop a reliable macroscopic numerical model capable of accurately estimating the heat generation and propagation during the reaction. A small-scale experiment is used to validate the numerical model, which approaches the experiment as a 2-D axisymmetric geometry within multiple regions. The reaction is modeled with a simplified zero-order kinetic model assuming a constant kinetic rate for all chemical species. A porous model assesses the impact of porosity on the overall heat diffusion, and a source-based phase change model is employed to evaluate the melting of the chemical species and the outer tube. Also, a disruptive model is included to consider the reaction between only condensed phases. The experimental validation demonstrated a good agreement between the numerical results with the disruptive model and transient temperature profiles measured experimentally. Varying the kinetic rate and porosity suggests that a slower reaction and denser mixture can enhance the heat transfer towards surrounding materials, potentially benefiting future applications in well sealing.