Laboratory experiments of high-temperature steam and nitrogen foam compound flooding

In order to study the influences of different factors on plugging property of foams and oil recovery enhance effect of high-temperature steam and nitrogen flooding, the effects of foaming agents concentration, temperature, gas-liquid ratio, permeability and oil saturation on the plugging ability of 3 foaming agents, the effects of foaming agent concentration and the ratio of steam and nitrogen on the plugging poverty of steam - nitrogen foam compound flooding system and the flooding tests of various foaming agents in single pipe and dual-pipe were all studied by experiments. The results indicated that the foam resistance factor increased with the increase of the concentration, gas-liquid ratio and permeability and the trend slowed down in the later period of experiments. The optimal concentration was 0.5% and the optimum gas-liquid ratio was 1:1. On the other hand, the resistance factor reduced with the oil saturation increasing and the foam lost its plugging ability when the oil saturation was greater than 0.2. The resistance factors of 1# and 2# foaming agents dropped with temperature added, but that of 3# increased. The suitable mass fraction was 0.6% and the ratio of steam to nitrogen was 3:2 for steam and nitrogen foam flooding. The oil recovery of 2# and 3# foaming agents increased by 20.82% and 17.05% respectively. In the process of steam and nitrogen foam flooding, the increased sweep efficiency and displacement efficiency of 2# were 13% and 24.6% while those of 3# were only 9.05% and 21.9%; therefore the performance of agent 2# is superior to that of 3#.