The Experiment Study of Extra Heavy Oil Developed by Air Injection Assisted Huff and Puff

In the middle and late stages of the cyclic steam stimulation (CSS) process, a series of problems exist, including low formation pressure, poor single-well production capacity, high water cut, low oil-steam ratio and energy utilization efficiency. Air injection assisted cyclic steam stimulation is a promising technology for heavy oil exploitation. For a typical heavy oil sample, laboratory experiment was done to investigate the contribution of air injection on the CSS process in comparison with nitrogen injected, with the air injection timing and gas injection volume being optimized. The result indicate that gas injection assisted CSS can significantly extend production cycle time and improve oil recovery; Turning into gas injection assisted CSS has a better exploitation effect than that in the later period with the recovery factor increasing by 15.13%. Further experimental findings demonstrate that, within a certain range, the exploitation effect has a positive correlation with the air injection volume—the greater the air injection volume, the better the development effect, with the maximum increase in recovery efficiency reaching 19.83%.