Preparation and performance evaluation of ultra high temperature corrosion inhibitor for acidizing

Abstract To develop efficient acid corrosion inhibitors suitable for oilfield environments, this study integrates quantum chemical calculations and molecular dynamics simulations to assess four Mannich base compounds. The molecular structures were analyzed in terms of electronic properties and adsorption behavior on Fe surfaces. All four molecules exhibited multiple reactive centers—including carbonyl groups, C = C bonds, amino groups, and aromatic rings—facilitating electron exchange and protective film formation via chemisorption. Among them, compound X4 exhibited the highest adsorption energy and the lowest diffusion coefficient for corrosive species (H₂O/H₃O⁺), indicating superior theoretical corrosion inhibition performance. Based on these findings, X4 was synthesized through a two-step Mannich reaction. The optimal synthesis conditions were determined using single-factor experiments and orthogonal design optimization. The synthesized product was characterized using FTIR(Fourier Transform Infrared Spectroscopy). The corrosion inhibition performance was evaluated by weight-loss measurements under varying temperatures, acid concentrations, and metal substrates. X4 exhibited excellent corrosion inhibition for N80, 13Cr, and P110 steels, maintaining its effectiveness at temperatures up to 180 °C. The adsorption of X4 followed the Langmuir isotherm model and was predominantly governed by chemisorption, aligning well with simulation predictions. This integrated computational–experimental approach offers a robust framework for the rational design of high-performance corrosion inhibitors suitable for harsh acidic environments in the petroleum industry.