Study On Mechanism Of CO₂-assisted Water Control For Steam Stimulation Horizontal Well With Bottom Water

There are abundant reserves of heavy oil with bottom water in China,which is mainly produced by steam huff and puff.However,in the actual production process,problems such as bottom water channeling are prone to occur,resulting in high residual oil saturation and water content.When water flooding occurs after steam huff and puff,CO₂ injection can effectively control water and increase oil,so as to realize the goal of enhancing recovery.Accordingly,it is of great significance to study the mechanism of CO₂-assisted water control for steam stimulation horizontal well with bottom water.This paper takes reservoirs in Spring 10 well area of Chunguang oilfield as an example to study the characteristics of water channeling under three different water channeling geological modes,and comprehensively analyzes the mechanism of CO₂-assisted water control measures in the reservoir through numerical simulation and physical simulation experiments.Secondly,according to different water channeling situations,typical wells are selected for numerical simulation analysis with CMG to study the effect of CO₂ water controlling measures and the technical boundary of CO₂ water control in bottom water channeling is established.Finally,the water controlling effects of five typical wells under different geological modes are compared and the parameters of the optimal sealing method are optimized.Research results show that the CO₂ in the reservoir will exist in two forms:gas phase and oil phase.The gas phase CO₂ plays a role of water controlling,and the dissolved CO₂will increase production.The lower the reservoir pressure and the larger the gas injection volume,the better the CO₂ water control effect.The measure of CO₂-foam composite water control technology is best for the spring 10II1-3-8 well;N₂-CO₂ measure is best for the spring 10II2-5-7 well;CO₂-gel composite sealing measure is best for the spring 10II2-5-10,spring 10II2-6-10 and spring 10II2-6-11 wells.The results of this paper can provide specific method and guidance for the analysis of CO₂-assisted water control and stimulation technology in similar reservoirs.