Derivation of NMR T2 relaxations of water in crude oil samples from the half-height peak width

The relation of NMR spin-lattice and spin-spin relaxation times (T1 and T2) to the viscosity and diffusion coefficient of crude oil has been studied in detail for a long time. In oil and water emulsions in oil, fracture characterization, permeability estimation, dynamics of water and oil in granular packages and rocks, and NMR relaxation dispersion properties of crude oil are also examined by the NMR technique. The vast majority of oil studies have been done by low field NMR. However, low field NMR devices cannot distinguish the peaks from each other. This is because NMR devices give a composite peak consisting of overlapping peaks. To evaluate these peaks, a mathematical technique called relaxion inversion is used instead of the traditionally used Fourier Transform technique. However, the techniques used in the relaxation time measurements are time consuming. In addition, so-called Radiation Dumping may not allow for settling time measurements in high areas. On the other hand, the derivation of the 1/T2 relaxation rate from the line half-width of NMR peaks has been the subject of frequent studies in recent years. The purpose of this thesis is to derive the time 1/T2 from the half-line widths of the water peaks obtained from the NMR spectrum of the petroleum liquid. For this purpose, 23 crude oil samples were taken from different wells in Batman region. Mixtures were prepared by adding 0.06 mL of oil and 0.94 mL of deuterochloroform (CDCl3) from each well. In addition, 5 different concentration sets were prepared by adding increasing amounts of fluid in 0.02 mL steps to 0.90 mL D2O. 20% water was added to the petroleum fluid taken from another well, which did not peak H2O. After preparation, the mixtures were immediately transferred to 5 mm diameter NMR tubes and NMR measurements were taken immediately. Measurements were carried out with a 400 MHz NMR spectrometer using a single pulse sequence. Peak half-line widths were found with the aid of a cursor from the half- height of the water peaks. The spectrum obtained with 400 MHz NMR gives two peaks, one around 1.56 pp and the other around 4.71 ppm. The spin-spin relaxation rates (1/T2) of these peaks were calculated from the relation between the 1/T2 and half-height line width. Experimental data are consistent with the literature and show that 1/T2 values can be obtained from the theoretical relation. The water peak at 4.71 ppm appear only the spectrum of some samples, and it was not in the spectrum of the sample to which we added water. This finding is useful for determining whether there is water in the oil of a well. Dependence of the line width on oil content was found to be linear. This is consistent with the rapid chemical exchange of water molecules between the bound and free phase.