超临界CO2吞吐提高页岩油采收率实验评价OA

The effects of gas injection pressure,huff-n-puff times,and permeability on shale oil recovery rate were systematically studied through CO2 huff-n-puff experiments and nuclear magnetic resonance testing under high temperature and high pressure conditions,and the utilization characteristics and remaining oil distribution of shale oil in different pore structures were quantitatively analyzed.The ex-perimental results showed that the micropores(r<0.026 μ m)and small pores(0.026≤r<0.325 μ m)in the experimental shale were well developed,with a volume ratio of 65.23%～80.16%.The optimal gas injection pressure is 15～18 MPa,the optimal huff-n-puff times is 4,and as the permeability increases,the huff-n-puff recovery rate also increases.CO2 huff-n-puff prioritizes driving crude oil in mesopores(0.325≤r<4.064 μ m)and macropores(r≥4.064 μ m);As the huff-n-puff times increases,the crude oil utiliza-tion proportion in small pores and mesopores first increases and then decreases,while the crude oil utilization proportion in macropores gradually decreases and the crude oil utilization proportion in micropores increases.The remaining oil is mainly concentrated in micro-pores and small pores,with volume proportions of 49.83%～67.14%and 31.56%～46.27%,respectively.Further improving the re-covery rate of crude oil from pores with a pore size less than 0.325 μ m is the key to achieving increased and stable production of shale oil.