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A series of experiments was conducted to quantify foamy oil recovery under different conditions, including the pressure depletion rate, solution gas-oil ratio (GOR), and oil viscosity. As indicated by the experimental results, at higher-pressure depletion rates, solution GOR, and oil viscosity, the foamy oil ultimate recovery tends to be higher. The foamy oil phenomenon can occur when the pressure depletion rate, solution GOR, and oil viscosity exceed certain values. Based upon experimental results, multiple regression analysis was used to establish a mathematical expression of the relationship between dimensionless foamy oil recovery ( R eD ) and the main factors affecting it, including the dimensionless pressure depletion rate (Δ p rD ), the dimensionless solution GOR ( R sD ), and the dimensionless oil viscosity ( μ D ). The computed results showed the weighted values of the effects of lnΔ p rD , ln R sD , and ln μ D on ln R eD to be 0.653, 0.211, and 0.136, respectively, which indicates that improving the pressure depletion rate may be the most effective approach to increasing the amount of foamy oil recovered. The uses and limitations of the correlation were validated using verification experiments and are discussed. Suggestions for rendering foamy oil recovery more efficient can provide useful guidance for the development of heavy hydrocarbon reservoirs. [ABSTRACT FROM AUTHOR]

To promote CO 2 utilization and protect the environment, CO 2 is often employed to enhance oil recovery. Meanwhile, injection of CO 2 –CH 4 mixtures can offer better mobility ratios and delay water breakthrough resulting in the favorable oil sweep efficiency. The gas-alternating-water (WAG) flooding in rhythmic hydrocarbon reservoirs has been studied by simulation software. The difference between water and CO 2 –CH 4 flooding lies in the different density and viscosity among CO 2 , CH 4 , oil and water. Water tends to displace oil along the lower reservoir; inverted rhythmic reservoir may slow down the trend. CO 2 and CH 4 tend to displace oil along the middle-upper and upper reservoir, respectively; positive rhythmic reservoir may slow down the trend. Therefore, a homogeneous reservoir should be given priority in WAG flooding, followed by positive rhythmic reservoir. [ABSTRACT FROM AUTHOR]