Contact Characteristics and Characterization Methods of CO₂ and Crude Oil in Visual Porous Medium

In this article, the vertical static variation characteristics of CO 2 and crude oil in porous medium under different experimental pressures are studied by using the CO 2 miscible visual displacement device jointly developed. The process of change at the CO 2 and crude oil interface is characterized by relative height and dissolution expansion rate. Experimental results demonstrate that with the increase of pressure, CO 2 gradually reaches a supercritical state with strong extraction and mass transfer capacity, and CO 2 ‐crude oil exhibits different contact forms under different pressures. Under the same pressure, there are also significant differences in contact forms between visual tube and porous medium. The existence of porous medium weakens the mass transfer and diffusion abilities between CO 2 and crude oil and reduces the extraction of light components by CO 2 . In porous medium, the relative height of crude oil is a power function of time, which is 1/5 ≈ 3/10 of that in visual tube. And the dissolution expansion rate of CO 2 and crude oil exhibits a negative logarithmic correlation with time, which is 1/4 ≈ 2/5 of that in visual tube. The impact of porous media on relative height and dissolution expansion rate of crude oil becomes more pronounced as the pressure decreases.