Study on oxidation kinetic behavior and oxidation exothermic ignition-inducing characteristics of crude oil

Air injection oil displacement is a highly promising enhanced oil recovery technology due to its wide gas source availability, low cost and strong reservoir adaptability. The auto-ignition behavior and oxidation characteristics of crude oil are critical to its combustion performance and upgrading efficiency. This study addresses the limitations of existing research, particularly the singular methods for determining auto-ignition and the lack of quantitative basis. Using a light crude oil from western China, we employed a combined approach with TG, PDSC, and ARC to investigate its oxidation and exothermic behavior. Special emphasis was placed on analyzing the auto-ignition temperature, sustainability of exothermic reactions, and kinetic parameters, clarifying oxidative auto-ignition feasibility. Kinetic models were established using two typical iso-conversional methods to quantify reaction parameters for both LTO and HTO stages. The results indicate that the primary reaction below 175°C is distillation and volatilization, with LTO and HTO mass loss rates of 81.5% and 18.5% respectively (10°C min ^− 1 ), and corresponding enthalpies of 15.8668 kJ g ^− 1 and 6.1395 kJ g ^− 1 . High pressure conditions significantly inhibit the volatilization of light components, elevating the LTO exothermic intensity to 55 mW mg ^− 1 —170% higher than under atmospheric pressure. The total heat release ranges from 19.2164 to 37.0479 kJ g ^− 1 , with high pressure reducing the HTO initiation temperature by 71.8°C. Under reservoir conditions, LTO exotherm occurs, and the auto-ignition temperature is determined as 262.8°C. Sustained exothermicity confirms that air injection is suitable for this light oil reservoir. This study provides important guidance for designing air injection schemes in similar reservoirs.