This work presents a study carried out in oil wells to analyze the effects on their structure due an exothermic reaction of termite in order to create a plug capable of replacing the currently ones of cement. The study focuses on the analysis of oil well portion considering a cylindrical multilayer hollow model with layers of: steel, cement and sedimentary rock. At hollow cavity, a thermite reaction will occur generating heat and creating a plug. The exothermic reaction is transient and will be modeled by a numerical model based on the Finite Element Method, FEM, whose thermal field generated will be a input of the structural numerical model also modeled using FEM. The simulations were carried out via ANSYS© in which stress curves and deformations generated in the medium were analyzed to verify the impact of thermally affected zones and investigate how steel, cement and sedimentary rock reacted during and after the termite reaction.