Comprehensive optimization of gas injection parameters for oxygen-reduced air flooding in Chang 8 reservoir of Honghe oilfield

In order to explore and study the feasibility of improving the recovery rate of fractured-tight reservoirs by reducing oxygen air flooding, a dual medium and multi-component numerical simulation model is applied, and the evaluation indexes are oil increment, oil change rate and oil cost per ton, combined with the on-site implementation process conditions. The results show that when the oxygen content of injected gas is 5%, the best economic benefit can be achieved and the highest oxygen content of the produced gas is 3.95%. It is safe, controllable and the corrosion rate is slowed down. To prevent gas channeling, the optimized ratio of air/foam slug should be 5:1, which can delay gas channeling and expand sweep volume. The daily gas injection volume of a single well is optimized to be 1.5×104 Nm3, the gas injection pressure is 20～25 MPa, and the total injection volume is controlled to be 4 000×104 Nm3. The research results in the well group can achieve good economic benefits, which lays a technical foundation for deepening the application of oxygen-reduced air flooding and improving the recovery factor of fractured tight reservoir.