Experiments on the flooding efficiency of different CO2 injection techniques in tight oil reservoirs of Jilin Oilfield
Using cores and oil samples from Fuyu tight oil reservoir of Jinlin Oilfield,experiments of CO2 huff-n-puff,CO2 flooding,surfactant-CO2 compound huff-n-puff and surfactant-CO2 compound flooding were carried out to analyze the differences in the efficiency of various CO2 injection techniques.Nuclear magnetic resonance scanning technology was used to monitor the distribution of remaining oil,and the crude oil production degree were clarified.The results show that CO2 huff-n-puff is the most effective in improving oil recovery,followed by surfactant-CO2 compound flooding.CO2 flooding is slightly less effective,and surfactant-CO2 compound huff-n-puff is the least effective.After four huff-n-puff cycles,the crude oil recovery degree of compound huff-n-puff is significantly lower than that of CO2 huff-n-puff,but the decrease in the crude recovery of a single cycle of compound huff-n-puff is smaller,and there is still potential for enhanced oil recovery after four huff-n-puff cycles.Based on pore size and saturated oil volume,the pores are divided into large,medium,small and micro pores.Large and medium pores make the main contribution to the crude oil recovery.Compared to CO2 huff-n-puff and CO2 flooding,surfactant-CO2 compound huff-n-puff and surfactant-CO2 compound flooding significantly increase the degree of crude oil production in micropores.
NETL
NSTL
万方数据
