Numerical simulation study on enhanced oil recoveryby air injection process in Shengli Oilfield

Air injection LTO (low temperature oxidation) process is a new technique economically for enhanced oil recovery (EOR) from light or medium oil and low permeability reservoirs. This paper aims at studying the oxidation kinetics of light oils and building up the reservoir simulation models for the LTO process. Oxidation experiments at reservoir temperatures have been conducted for light oil samples of the Shengli Oilfield (China), and the data were used for deriving the kinetics model of LTO reactions, by matching the contents of oxygen and carbon dioxide in the oil displacement experiment. Conceptual reservoir simulation models have been developed for studying the EOR mechanisms and the affecting factors of the air injection LTO process, using the reservoir parameters of Luo36 Block. Moreover, air injection process was compared with nitrogen injection in terms of oil displacement efficiency and economics. The simulation results suggest that there is a good match with experimental results. Besides, reservoir temperature, air injection rate and residual oil saturation (before air injection) are important parameters that can greatly affect the consumption of oxygen and incremental oil recovery, while reservoir dip angle, layer perforations can also affect the process. Compared with nitrogen gas injection, the advantages of air injection are the low cost in gas source and high oil displacement efficiency due to thermal effect of the LTO reactions.