Heat Release Model for the Low Temperature Oxidation of Heavy Oils from Experimental Analyses and Numerical Simulations

Low temperature oxidation (LTO) of heavy oils involves many complex reaction mechanisms that are important for the success of ignition and front propagation during in situ combustion (ISC). In this study, experiments and numerical simulations were combined to investigate the heat release characteristics of LTO. Pressure differential scanning calorimeter (PDSC) experimental analyses were used to measure the heat release for various heating rates and pressures under temperatures from 50 to 350 °C. The heat release curves for the various heating rates were consistent with a theoretical Arrhenius analysis, indicating the feasibility of simulating the heat release during the LTO reaction by an Arrhenius equation. The pressure also had a significant effect on the LTO heat release. The results show that the total amount of heat release from LTO is positively correlated with pressure but that the oil consumption rate did not change. A numerical model was used to simulate the PDSC experiments to study the LTO reaction kinetics based on an exothermal Arrhenius reaction model to calculate the heat release rates. The kinetic parameters were obtained using the history matching method with different reaction enthalpies at different pressures to model the effect of pressure on the heat release. The reaction model and kinetic parameters successfully predicted the LTO heat release rates; therefore, these parameters are valuable tools for engineering applications.