CO

2

is widely used as a displacement agent in oil displacement because of its unique physical properties and its chemical reaction with crude oil. But pure CO

2

gas flooding is prone to gas channeling. So the application of CO

2

in the foam flooding process make CO

2

can not only play its own role in oil displacement

but also realize fluidity control and reduce the possibility of gas channeling. In this study

the stability

particle size change and percolation characteristics of CO

2

foam with different particle sizes and the same chemical composition are experimentally studied

the change rule of the influence of particle size on foam performance is obtained

and the influence mode is anal

yzed and discussed. The results show that the smaller the bubble size

the better the stability of the foam system

the stronger the blocking ability

and the slower the particle size changes over time. Changing the preparation method to reduce the particle size of the foam system can effectively improve the foam’s stability and EOR capacity.