Mechanism Identification and Differentiated Control of CO2 Gas Channeling in the Chang 6 Low-Permeability Reservoir of the Qiaojiawa Oilfield

CO2 channeling limits the effectiveness of immiscible flooding in the Chang 6 low-permeability reservoir of the Qiaojiawa Oilfield. This study integrates core- and fluid-property data, slim-tube minimum miscibility pressure (MMP) measurements, facies-controlled geological modeling, and CMG-GEM compositional simulation to examine channeling controls and screen differentiated treatments. The initial reservoir pressure (12.90 MPa) was below the reported CO2–oil MMP of approximately 22.15 MPa. The simulated responses are consistent with the combined effects of mobility contrast and high-permeability pathways. Three representative well groups were classified as weak, moderate, and strong using permeability contrast, earliest breakthrough, and peak gas–oil ratio (GOR). At year 10, simulated recovery factors were 19.2% for continuous injection, 20.7% for intermittent gas injection (IGI), 23.4% for water-alternating-gas injection (WAG), and 27.2% for foam-assisted mobility control (FAM). These results describe the prescribed schedules and provide a basis for preliminary treatment screening.