In this paper, extraheavy oil recovery assisted by CO₂ and an oil-soluble viscosity reducer under deep reservoir conditions was experimentally investigated. Specifically, the viscosity reduction efficiency of the oil-soluble viscosity reducer was measured, and the morphological characteristics of the asphaltenes in the heavy oil were observed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). CO₂ huff-n-puff experiments were carried out to determine the oil recovery factor and the oil/gas exchange ratio. The properties of the produced oil were tested, and the oil saturation in cores was scanned through nuclear magnetic resonance (NMR). The experimental results show that the oil-soluble viscosity reducer decreases the viscosity of extraheavy oil by decreasing the asphaltene concentration and the size of the asphaltene aggregations in the extraheavy oil. CO₂ huff-n-puff assisted by an oil-soluble viscosity reducer can considerably improve the oil recovery of extraheavy oil. When the concentration of the viscosity reducer increases from 0 to 10 wt%, the oil recovery factor after five cycles increases from 18.74 % to 34.44 %, and the foamy oil effect is stimulated. An economic concentration range of 1–3 wt% is suggested for field CO₂ huff-n-puff applications. With increasing CO₂ huff-n-puff cycles, the cyclic oil recovery factor and oil/gas exchange ratio sharply decrease. The oil recovery and oil/gas exchange ratio of the first two cycles are considerably higher than those of the last three cycles. The oil saturation tested by NMR shows that the sweep area of CO₂ huff-n-puff is limited to the first two-thirds of the core, indicating that the injection volume of CO₂ should be increased with each successive cycle, and the well distance should be suitably decreased to improve the oil recovery of the whole reservoir.

本文对深层油藏条件下CO ₂和油溶性降粘剂辅助的超稠油采收率进行了实验研究。具体而言，通过扫描电子显微镜（SEM）和原子力显微镜（AFM）测量了油溶性降粘剂的降粘效率，并观察了重油中的沥青质的形态特征。一氧化碳₂进行了nuff-n-puff实验以确定油的采收率和油气交换率。测试了采出油的性质，并通过核磁共振（NMR）扫描了岩心中的油饱和度。实验结果表明，油溶性降粘剂可通过降低重油中沥青质的浓度和沥青质聚集体的尺寸来降低重油的粘度。一氧化碳₂油溶性减粘剂的辅助作用可大大提高超稠油的采油率。当降粘剂的浓度从0增加到10重量％时，五个循环后的油采收率从18.74％增加到34.44％，并且刺激了泡沫油作用。对于野外CO ₂吹气-正吹气应用，建议经济浓度范围为1-3 wt％。随着CO ₂ huff-n-puff循环的增加，循环油采收率和油气交换率急剧下降。前两个循环的采油率和油气交换率显着高于后三个循环。通过NMR测试的油饱和度表明，CO ₂的波及面积huff-n-puff仅限于岩心的前三分之二，这表明应在每个后续循环中增加CO ₂的注入量，并应适当减小井距以提高整个油藏的采油率。