Experimental investigation of microscopic CO₂ injection for enhanced oil recovery in tight reservoirs

Oil exploitation of tight reservoirs has gained significant importance lately. Some researchers have defined tight reservoirs as those characterized with permeability lower than 0.1 mD. However, permeability is an absolute value, and tight reservoirs have complex pore systems that require a detailed geological and petrophysical rock characterization for optimal recovery process. Enhanced recovery of tight oil reservoirs is challenging because of possible oil bypass due to high capillary forces. Increasing displacing fluid viscosity will provide stable displacement and preventing any viscous fingering but will lower the displacing fluid injectivity. On the other hand, lowering the displacing fluid viscosity can lead to viscous fingering resulting in increased residual oil. CO2 injection, a common EOR technique, can positively impacts pore fluid displacement of tight reservoirs, including micropores. However, the main challenge of CO2–EOR in tight reservoirs is the complex nature of pore systems that can lead to unfavorable displacement....