将磁共振成像技术应用于高压条件下多孔介质内渗流特性的可视化研究中.为40mm内径微成像探头设计了专用的填砂式岩心夹持器,并将该夹持器应用于CO2非混相驱和混相驱实验中.动态连续二维成像分辨率为0.21mm×0.21mm,基本接近于实验所用玻璃砂尺寸,从而实现了对CO2非混相驱过程中气体窜流通道的形成过程、CO2混相驱过程中塞状驱替前缘的推进过程及多孔介质内油相赋存状态的连续可视化观测.发现在气态CO2非混相驱油实验中,由于气油两相黏度差和密度差的影响,指进和窜流现象较明显,波及范围较小,残余油饱和度为54%;在超临界CO2混相驱油实验中,塞状驱替前缘基本保持匀速推进,可以有效地抑制指进和窜流现象的发生,波及范围较大,最终残余油饱和度为20%.可见,超临界CO2混相驱油技术可显著提高采收率.%For the visualization of flow in porous media in high pressure conditions using magnetic resonance imaging（MRI） technique,a new glass-packed core holder is designed for the MRI system with a 40 mm inner diameter micro-imaging probe.This apparatus is demonstrated through observation of CO2 immiscible and miscible displacement,and the dynamic spatial resolution of 2D images is 0.21 mm×0.21 mm,close to the experimental glass bead size,so the fundamental characteristics of the two-phase flow process,such as onset of CO2 channeling in immiscible displacement,the advance of piston-like frontal of CO2 in miscible displacement and the distribution of oil in porous media can be accurately detected.It is found that for CO2 immiscible displacement,due to the difference of fluids viscosity and density,the phenomenon of CO2 channeling or fingering is obvious,so the sweep efficiency is small and the final residual oil saturation is 54%;for supercritical CO2 miscible displacement,the velocity of CO2 frontal is uniform,the phenomenon of CO2 channeling or fingering is restrained effectively,and the sweep efficiency is high and the final residual oil saturation is 20%.So supercritical CO2 miscible displacement can enhance oil recovery evidently than CO2 immiscible displacement.
展开▼
