Effect of Miscibility Condition for CO2 Flooding on Gravity Drainage in 2D Vertical System

In CO2 injection process, the densities and viscosities of oil and CO2 are the main variables determining the gravity drainage that can cause early CO2 breakthrough. Once the injected CO2 moves toward top of the reservoir, CO2 front contacting with oil is gravitationally unstable, which leads to the decrease in oil recovery. Several researchers showed the importance of miscibility condition and gravity drainage effect on the oil recovery duringCO2 injection. Asghari et al and Torabi et al. conducted experiments and simulation study considered miscibility condition in fractured system. They showed the oil recovery may decrease far above the miscibility. 

Trivedi et al. also conducted experimental work about effect of CO2 injection rate at various miscibility conditions in fractured reservoir. Kulkarni et al. reported gravity drainage effect for Gas Assisted Gravity Drainage (GAGD) process under immiscible and miscible conditions. Nasrabadi et al. conducted the simulation study to investigate the effect of density in the 2D vertical reservoir and shown significant effect of gravity and heterogeneity. Although a number of researchers have investigated about CO2 flooding under the various miscibility conditions and the gravity drainage mechanism, none of researches have been done in vertical oil reservoir. Read more................