The pore utilization characteristics of CO

2

during shale oil displacement are a crucial indicator for evaluating its effectiveness in enhancing shale oil reservoir recovery rates. Therefore

experiments on supercritical CO

2

displacing shale cores were conducted in the laboratory

and nuclear magnetic resonance（NMR） online core scanning technology was used to study the pore utilization characteristics and patterns of CO

2

displacement in shale oil reservoirs. The results indicate that immiscible flooding by supercritical CO

2

mainly develops the oil in shale pores with radius of 0.1~3.0 μm

but the oil content in pore radius less than 0.008 μm actually increases. The analysis shows that CO

2

b

rings shale oil from large pores into small pores through pressure difference and diffusion effect in the shale layer and makes oil undergo adsorption and retention. After a displacement time of five hours

the recovery rate of shale oil by CO

2

displacement reached 35.7%

indicating a relatively effective oil displacement result.