Dependence of 400 MHz NMR Peak Line Widths of Crude Oil on Well Characteristics

Today, magnetic field inhomogeneity in high-field NMR machines is minimized by proper shimming of the machine and extensive dilution of the sample with deuteron solvents. Hence, the line width (LW) measurements of the NMR peaks are reliable for NMR studies. This study is aimed at examining the relationship between the crude oil properties and the LW values of the CH 2 and CH 3 peaks and the relationship between the LW of water in crude oil and the percentage of water. A set of 22 mixtures was prepared by adding 0.02 mL of each crude oil to each 0.98 mL of CDCl 3 . A suitable NMR spectrum, including the water peaks of the mixtures, was obtained with a spectrometer operating at 400 MHz. Paraffinic CH 2 and CH 3 peak LWs vary from well to well. Paraffinic CH 3 LW decreases nearly linearly with American Petroleum Institute gravity. In addition, the LW of the water peak at 4.75 ppm is strongly related to the percentage of water in crude oil. The mixtures used in this study provide the appropriate NMR peaks for CH 2 , CH 3 , and water in crude oil. NMR peaks of water in crude oil were displayed for the first time in the high field. Some of the previous results obtained in the low-NMR field were found. Therefore, this study suggests an additional approach for high-field NMR studies in petroleum chemistry.