Development and Application of a Modified Superheated Steam Flooding Assisted by N2 Foam and High-Temperature Resistant Gel

Abstract Superheated steam has a smaller density and a larger specific volume than conventional saturated steam, and has a stronger override effect in heavy oil reservoir. As most of heavy oil reservoirs have strong heterogeneity because of high porosity and permeability. Therefore, the steam injection profiles vary greatly and vertical producing degree of reservoirs is very low. Nitrogen with a large compression coefficient, large volume coefficient, large expansion volume capacity, can feed the formation energy and acceleratively drive heavy oil efficiently. For another, the surfactant in the foam can reduce the oil-water mobility ratio. High temperature-resistant gel can seal steam breakthrough channel due to its high permeability. Nitrogen foam and gel flooding can increase the superheated steam swept volume, improve the effect of superheated steam flooding in heavy oil thermal recovery. The injection parameters of nitrogen foam and high-temperature resistant gel were systematically studied by numerical simulation combined with physical simulation method in this paper. Gel, foaming agent, nitrogen injection sequence and injection method determined the improvement degree of steam injection profile modification. The results showed that under the injection rate of foaming agent was 240m3/d, the daily injection of nitrogen was 2000m3/d, the total injection amount of foaming agent was 16,000m3 in early slug injection, the effect of thermal recovery was the best. Application of this technology in KMK heavy oil field can enhance heat insulation effect of wellbore, decreased thermal lost by 15.5%, modified superheated steam injection profile by 36.3%, increased vertical producing degree of the reservoirs to 65.8%, feed formation energy in high efficiency. The superheated steam injection profile modification method by N2 foam and gel shows great economic prospect as a way of plugging steam breakthrough channel, controlling steam override and enhancing heavy oil recovery.