Relate NMR Relaxation Times of Pure Components and Mixtures with Viscosities and Diffusion through Application of Corresponding States

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A versatile NMR probe has been designed and constructed. This probe is capable of performing low signal to noise spin- lattice relaxation and diffusion coefficient measurements at pressures up to 600 atm over a temperature range of -20 to 200oC. The probe is also configured so that vapor liquid equilibrium can be established in the sample at these temperatures and pressures. In the immediate future the probe will be used to measure relaxation times (T1) and self diffusion coefficients in 13CO2 as a function of temperature and pressure. The only T1 measurements on this important fluid are the four isochores measured by Smith and coworkers (1986). Several investigators have measured the self- diffusion coefficient of CO2 over the temperature range accessible to the probe, but the measurements are confined to pressures less than 200 atm. After the pure CO2 measurements, mixtures of CO2 and n-hexadecane will be studied. This data will then be correlated with classical transport properties. This type of correlation remains relatively unexplored for mixtures. A global corresponding states treatment will also be attempted throughout this project. NMR can supply a wealth of information about the motions of molecules in all phases of matter. From the relaxation times, the rotational and translational motions may be investigated. The diffusion coefficients, measured by the spin-echo method, provide a means to investigate translational motions. In the past several years NMR imaging has been established as a valuable tool in the investigation of fluid flow in porous media. A major challenge in the usefulness of this technique lies in relating the NMR measurables to traditional thermodynamic and transport properties. The interrelationship is shown in Figure 1. The purpose of our current NMR program, is to further develop and quantify some of the relationships between NMR measurables, transport properties, and state variables. One area which would benefit greatly from the development of these relationships is the interpretation and quantification of NMR images. Practical use of NMR imaging requires a correlation to bridge the NMR data with traditional engineering analysis.