Construction of Anti-channeling and Plugging Agent Assisted Oxygen-Reducing Air Flooding System and Its EOR Effects

Relying on the oxygen-reduced air flooding (ORAF) and anti-channeling test in Changqing Oilfield A test area, the static performance evaluation experiments of different plugging agents such as particle size distribution, hydration expansion, gel formation time, and gel formation strength were carried out. The particle size distribution and hydration swelling properties of microspheres (PMs) and PEG were compared, and a low-concentration weak gel system was optimized: 0.1% HPAM+0.1% organic chromium cross-linking agent. The double sand-packing tube model was used to simulate the experiments of gas flooding for enhanced oil recovery under the conditions of different permeability ratio reservoirs (55 ℃ and 12 MPa). After gas flooding for a while, PMs (0.15%), PEG (0.3%), and preferred weak gel system were injected for anti-channeling gas flooding, and the contribution of different plugging agents to improving the recovery degree of gas flooding was clarified. The research shows that gas flooding is carried out before the plugging agent injection, and the gas flooding recovery factor of the three plugging agents is very close under the same permeability ratio. With the increase of permeability ratio, the recovery degree of gas flooding decreases continuously. However, after the injection of the three plugging agents, the gas flooding continued, and the recovery degree of the gas flooding increased significantly. PMs assisted gas flooding is recommended for reservoirs with weakly dominant channels with a permeability ratio of less than 3. Reservoirs with a permeability ratio of less than 12 are more effective in PEG plugging. The weak gel system is suitable for fractures with higher permeability ratio. Reservoir. The research results can provide technical guidance for on-site gas channeling blocking agent-assisted ORAF in target reservoirs.