Analysis of Key Influencing Factors in Gravity-Assisted CO₂ Flooding for Enhanced Oil Recovery

The gravity-assisted CO₂ flooding technology has achieved good application results in the low-permeability reservoirs with small dip angles of the Changqing Jurassic System. However, there is still the problem that the main controlling factors for the effect of enhanced oil recovery are not clear at present. In order to analyze the impact on the effect of gravity-assisted CO₂ flooding to enhance oil recovery on core scale, 29 groups of core displacement experiments were conducted. The main controlling factors in descending order are miscibility degree, crude oil viscosity, initial water saturation in gas flooding, reservoir permeability, structure amplitude and dip angle (small dip angle). This study aims to provide theoretical support for area, well and layer selection for this technology in the Changqing Jurassic low-permeability oil reservoirs and for the subsequent promotion of process technologies.