Role of Vapor Phase in Oxidation/Combustion Kinetics of High-Pressure Air Injection (HPAI)

Abstract

Abstract Oxidation reactions and their kinetics are acknowledged to have a major impact on the success of air injection-based improved recovery processes. Vaporization of oil has been reported in the literature as a mechanism associated with kinetics of air injection processes; however, the parameters which control the vapor phase oxidation/combustion behavior have not been included in the studies of oxidation kinetics. In order to characterize the vapor phase oxidation/combustion behavior of light oils in high pressure air injection (HPAI) process, an experimental and a follow up numerical study have been conducted on a high pressure ramped temperature oxidation (HPRTO) reactor on a 37 ° crude oil and a pure hydrocarbon. The results of this study indicate that phase equilibrium between the liquid and vapor hydrocarbon and water components has a definite impact on the "flammability range" for vapor phase combustion at given temperature and pressure conditions. The observations also suggest the potential participation of vapor phase oxygen addition reactions in the supply of triggering energy for spontaneous ignition. Given the importance of vapor phase behavior on the amount and distribution of hydrocarbons available for reaction with oxygen, a comprehensive phase behavior study on the selected light oil was performed. The developed phase behavior model was then used in a hypothetical model to study the behavior of the vapor phase under conditions of HPRTO tests. The significance of this model is its capability to predict the theoretical injected-air/fuel ratio of the vapor phase assuming thermodynamic equilibrium.