Application of Low-Field NMR for the Determination of Physical Properties of Petroleum Fractions

We propose the use of the low-field H-1 NMR technique to predict various properties of petroleum fractions with degrees API ranging from 21.7 to 32.7. The experimental data obtained by standard methodologies (ASTM D-1218, D 445-06, D-664-06, D-2892, and D-4052) were correlated with the mean values of the H-1 transverse relaxation time in the range between 25 and 675 ms. Results of the present work showed good correlations between the NMR relaxation data with viscosity, total acid number, refractive index, and API gravity. The main advantage of the proposed method is its nondestructiveness, together with its speed and the fact that it does not require solvents/dilution. This allows the assessment of several properties of petroleum fractions simultaneously, based on the output of only one NMR experiment, leading to large economy in terms of energy, time, and costs.