Measurement Of Miscibility And Diffusivity Of Gas And Oil Based On MRI

CO2 enhanced oil recovery (CO2-EOR) can not only enhance oil recovery and economy benefit effectively, but also realize CO2 geological sequestration, it is an important displacement method both economically and environment-friendly. In order to enhance the economy of the CO2-EOR, it is necessary to research the MMP and the diffusion principle of CO/oil system experimentally. Besides, magnetic resonance imaging (MRI), a powerful analytical tool, has been shown to exhibit considerable potential for non-invasive multidimensional visualization of flow and transport in porous media.The experimental research on visualization and quantitative analysis of the process of CO2 diffusion and mass transfer in oil-saturated porous media was described. An MRI technique and pressure decay method to visualize directly the distribution of CO2 diffused into porous rocks containing oil was used. Based on the signal intensity, a rapid method for measurement and estimation gas diffusivity in liquid hydrocarbon-saturated porous media has been applied. Given the range of test temperature and pressure, the effective diffusivity increased as the initial given pressure increased. The results compared with conventional pressure decay method and other previous studies show good agreement. The method provided a rapid and accurate tool for further studies on gas diffusion in liquid-saturated porous media. A significant phenomenon, in which the effect factor of temperature was larger than the pressure. The non-iterative finite volume analytical technique was applied to calculate the diffusion coefficient of CO2 in liquid. The diffusion coefficient of CO2 is an exponential function of diffusion distance. The diffusion coefficient decreases as diffusion distance and time increase.The relationship between NMR relaxation signal and CO2 solubility, hexadecane density, MMP of CO2/n-hexadecane system is investigated experimentally. A good exponential relation was found between the relaxivity and the pressure of the CO1/n-hexadecane system, moreover the MMP could be predicted by this relation. Besides, the experimental results showed that the T1 was lengthened by the dissolution of CO2 while the T2 was shortened. The relaxivity of 1/T1 and 1/T2 had a linear relation along with the elevated solubility and density. The experimental findings have a significant impact on developing the potential NMR logging technique to monitor of the migration law of the reservoir fluid.