Abstract: To address the problem of low recovery rate by steam flooding in thin ultra-heavy oil reservoirs, an indoor two-dimensional physical simulation experiment of flue gas SAGP was conducted on ultra-heavy oil reservoirs with developed interlayers by taking shallow heavy oil in the Hashan area on the northern edge of the Junggar Basin as the study object to study the characteristics of steam chamber development and gas distribution, and to analyze the change law of oil, gas and water in the process of flue gas SAGP, so as to evaluate the potential of flue gas SAGP in thin ultra-heavy oil reservoirs to enhance recovery and optimize the timing and volume of flue gas injection. The study shows that the recovery degree of the thin ultra-heavy oil in the flue gas SAGP stage can reach 56%, and the cumulative oil-to-steam ratio is 0.21, so there is a large potential for recovery enhancement; the steam is injected together with the flue gas, the flue gas is located at the front edge of the steam chamber, and no low-temperature insulation zone is formed near the top of the oil layer and the bottom of the cap layer; the flue gas gathers at the front edge of the steam chamber, which hinders the lateral expansion of the steam chamber and slows down the steam overlap; when the steam chamber is extended to the bottom of the oil layer, the recovery rate is 54% to 56% by injecting 0.08 to 0.10 times the pore volume of flue gas. The research results can provide an important reference for recovery enhancement of thin ultra-heavy oil reservoirs.

Key words: ultra-heavy oil, non-condensable gas, SAGP, flue gas, physical simulation