This study aimed to investigate dynamic CO₂ drainage using high-resolution magnetic resonance imaging (MRI) technology. Gaseous and supercritical CO₂ were injected downward in brine-saturated porous media at different flow rates at 40 °C/6 MPa and 40 °C/8 MPa. These flow rates (0.015, 0.03 and 0.1 mL/min, under 10 Mt/year), as reflected in, were chosen according to the distance (1 km–100 m) from the injection well. Three stages were found from the change of signal intensity during CO₂ drainage: before the CO₂ front reached the field of view (FOV), breakthrough, and steady state. Channelling or drainage fronts immediately established through the large pores, and CO₂ travelled vertically through these channels until breakthrough. The breakthrough time decreased with increasing flow rates and was longer for ScCO₂ than gCO₂ at the same flow rate, resulting in a longer residence time for ScCO₂ in the sample. At low flow rates, the fingers first established along the larger pore spaces (especially at 0.015 mL/min) and then gradually extended into adjacent regions, resulting in a relatively flat interface. However, at high flow rates, the front moved along the larger pore spaces until breakthrough. The flow patterns for ScCO₂ drainage were more uniform than those for gCO₂ drainage. The pore volume fraction occupied by CO₂, as a quantitative parameter of the flow pattern, reflected that the sweep efficiency and pore space utilization were optimized at 0.03 mL/min (Ca = 4.35 × 10⁻⁹ for gCO₂ and Ca = 1.06 × 10^-8 for ScCO₂). The effect of the flow rate on the CO₂ saturation and distribution was analysed. At low flow rates, the saturation gradient along the porous media gradually reduced, but trend to be stable at high flow rates. Additionally, the saturation at breakthrough and steady state were observed to be linearly related to the maximum rate of change in saturation during CO₂ injection. Overly fast drainage results in relatively low saturation and an inhomogeneous distribution. The results can be applied to provide information for enhancing pore space utilization and improving sweep efficiencies during field storage.

这项研究旨在研究使用高分辨率磁共振成像（MRI）技术进行动态CO ₂排放。将气态和超临界CO ₂在40°C / 6 MPa和40°C / 8 MPa下以不同的流速向下注入饱和盐水的多孔介质中。反映的这些流速（0.015、0.03和0.1 mL / min，在10 Mt /年以下）是根据距注入井的距离（1 km–100 m）来选择的。从CO ₂排放期间的信号强度变化中发现了三个阶段：在CO ₂前沿到达视场（FOV）之前，穿透和稳定状态。立即通过大孔和CO ₂建立通道或排水前沿垂直穿过这些渠道，直到取得突破。在相同流速下，穿透时间随流速的增加而降低，对于ScCO ₂而言，其穿透时间比gCO ₂更长，从而导致样品中ScCO _2的停留时间更长。在低流速下，指状物首先沿较大的孔隙空间建立（特别是在0.015 mL / min时），然后逐渐伸入相邻区域，从而形成相对平坦的界面。但是，在高流速下，前沿沿着较大的孔隙空间移动，直到突破为止。为SCCO流动模式₂排水，均较GCO更均匀的₂排水。CO ₂占据的孔体积分数作为流动模式的定量参数，反映了扫油效率和孔隙空间利用率物在0.03毫升/分钟的优化（CA = 4.35×10 ^-9为GCO ₂和Ca = 1.06×10 ^-8为SCCO ₂）。分析了流速对CO ₂饱和度和分布的影响。在低流速下，沿多孔介质的饱和梯度逐渐降低，但在高流速下趋于稳定。此外，观察到突破和稳态时的饱和度与CO ₂期间饱和度的最大变化率呈线性关系。注射。排水过快会导致较低的饱和度和不均匀的分布。结果可用于提供信息，以提高孔隙空间利用率并提高野外储存期间的波及效率。