【摘要】 通过对天然致密岩心进行人工造缝，试验研究致密油储层CO₂吞吐开采特征，分析基质渗透率、裂缝数量对CO₂吞吐采出程度的影响；通过核磁共振，探究CO₂吞吐动用孔隙范围及剩余油分布。结果表明：随着基质渗透率从（0.1～0.2）×10^-3μm²增大至（0.4～0.5）×10^-3和（0.8～0.9）×10^-3μm²,无裂缝致密岩心采收率从15.81%分别提高至20.48%和26.18%,CO₂动用的最小孔径从0.034μm依次减小为0.023和0.012μm;在基质渗透率为（0.8～0.9）×10^-3μm²的含单一裂缝和多裂缝的致密岩心中，采收率分别进一步提高至41.45%和52.46%,CO₂动用的最小孔径减小至0.003和0.005μm;基质渗透率和裂缝对采收率的提高主要体现在吞吐前两周期，对第3周期采出程度影响甚小；孔径约为0.1μm的孔隙内的原油是多周期CO₂吞吐开采后期的主要增油来源；CO₂吞吐开采后，较高基质渗透率和多裂缝的致密岩心中剩余油分布更为均匀。更多还原

【Abstract】 The production characteristics of CO₂ huff and puff in tight oil reservoirs were studied using natural rock cores with artificial fractures. The effects of matrix permeability and fracture on oil recovery were analyzed, and oil-production via CO₂ huff and puff and the distribution of residual oil in pore size range were investigate using a nuclear magnetic resonance（NMR） method. The experimental results indicate that with the increase of matrix permeability from（0.1-0.2）×10^-3μm² to（0.4-0.5）×10^-3μm² and（0.8-0.9）×10^-3μm²,the oil recovery of the tight cores without fractures increased from 15.81% to 20.48% and 26.18%, and the minimum pore size of oil-producing decreased from 0.034 μm to 0.023 μm and 0.012 μm. In the tight cores with a single fracture and multiple fractures with matrix permeability of（0.8-0.9）×10^-3μm², the oil recovery increased to 41.45% and 52.46%,and the minimum pore size of oil-producing reduced to 0.003 μm and 0.005 μm.The improvement of oil recovery by matrix permeability and fractures mainly appeared in the first two cycles of the huff and puff process, but had little effect in the third cycle and so on. The crude oil in the pores of about 0.1 μm is the main production source in the later stage of multi cycles of CO₂ huff and puff production. The residual oil in the tight cores with high matrix permeability and multiple fractures is more evenly distributed.更多还原