Investigation of flue gas displacement and storage after the water flooding in a full diameter conglomerate long-core

Five full diameter cores were obtained from a conglomerate reservoir of Xinjiang oilfield. They were assembled into a full diameter long-core group, with a total length of 52.3 cm, 10 cm in diameter. With the full diameter long-core flooding system designed and produced in China, experiments were conducted to simulate depletion, water flooding, flue gas flooding, flue gas-water alternative flooding, CO2 flooding, and flue gas storage in the conglomerate reservoir, and the characteristics and effect of the flue gas flooding were evaluated. The study shows that full diameter long-core flooding experiment is more effective in simulating the gas displacement and percolation characteristics in the conglomerate reservoir. According to the experimental results, the flue gas produced from fire flooding can be used to enhance oil recovery of the water-drived conglomerate reservoir. The key to reaching a favorable development effect is to select the right timing, injection pressure and mode of flooding. In the middle of the water flooding stage, when the dominant percolation channel has not been formed, injecting flue gas and water alternatively after increasing reservoir pressure could avoid premature gas channeling and enhance oil recovery. During the flooding, the poisonous gas, H2S, was absorbed efficiently in cores and fluids, and flue gas was stored safely.