Low-field nuclear magnetic resonance for petroleum distillate characterization

Low field nuclear magnetic resonance (LF-NMR) has several applications in the oilfield industry such as in predicting the viscosity and evaluating porosity, permeability, fluid saturation of reservoir rocks, and the water content in fluids. However, the studies to determine the physical and chemical properties of petroleum distillates are uncommon. So, the aim of this study was to determine the physical and chemical properties of distillates using the transverse relaxation time (T-2) in the range from 73.43 to 1810.74 ms. LF-NMR was employed in this research, due to its rapid and non-destructive analytical method. From LF-NMR data, it was possible to estimate the molar mass, correlation index, characterization factor, API gravity, relative hydrogen index, and number of hydrogen in distillates obtained up to 350 degrees C. T-2 and the properties determined by standard methodologies (ASTM D-1218, D-445-06, D-664-06, D-2892, and D-4052) were strongly correlated. So, low field NMR constitutes an interesting alternative to ASTM methods. The results also show that changes in the chemical and physical properties depend on boiling point and molecular mobility. Besides, LF-NMR enabled the classification of the fractions into gasoline, kerosene, and light and heavy gas oil. (C) 2015 Elsevier B.V. All rights reserved.