Energy & Fuels, Vol.25, No.10, 4299-4304, 2011
Low-Temperature Oxidation of Oil Components in an Air Injection Process for Improved Oil Recovery
Air injection is an effective technique for improved oil recovery in light oil reservoirs. It is speculated that the main mechanism of the process is via spontaneous low-temperature oxidation (LTO) to consume oxygen and generate "flue gas" that displaces oil out of the reservoir. In this study, laboratory experiments have been conducted to study the effects of oil composition and main reservoir parameters on the kinetics of LTO, in a range of reservoir temperatures from 70 to 150 degrees C. Saturates, aromatics, resins, and asphaltenes (SARA) analysis and experiments using pure oil components were preformed to study the oxidation activity of different oil compounds and components. Reaction rates of typical light and heavy oil samples were also measured for comparison. Effects of temperature, pressure, water saturation, sand type, and residence time on reaction rates and products were investigated under static and dynamic conditions. The results indicate that different oil components exhibit different reaction activity under the LTO conditions. Heavy oils can be more readily oxidized than light oils at low temperatures. The data shed more light on the mechanisms of LTO reactions and can provide guidelines for reservoir selection and air injection process design.