Application to Identification and Correlation of Unknown Crude Oils by the IR-1HNMR Method

Abstract

In our previous paper (TEZUKA et al., 1980), we proposed characterization of crude oils by the infrared (IR) method combind with proton nuclear magnetic resonance (1HNMR). In this paper, we attempted to adopt the method in order to identify the crude oils, to judge the dissimilarity between the two crude oils, and to make a comparison of oil with its producing zone.IR and NMR spectra of known crude oil samples and unknown were measured, and log I0/I at 1600cm-1 of the IR, CH2/CH3 of the NMR spectra were plotted on the two dimentional diagram, respectively. If these plots were within tolerance limit of the error, two crude oils should be concluded as the same.We took Niibori-3W and 6W crude oils in the Shounai Oil-field, and Asahihara-1 and Koshijihara-2 crude oils in the Minaminagaoka Gas-field to examine whether the crudes were as the same or not. As their plots did not coincide in both cases, they were not estimated as the same. The conclusion agreed with that from the conventional method, such as comparison of distillation curves, specific gravity, etc. Sampling of crude oils was made twice from 12 wells in Abudhabi Oil-field in 20 months' interval. These 12 pairs of Abudhabi crudes were examined by the method. In some wells, IR and NMR specific values of the newer and the older samples were different, but in other wells both values agreed. So far as in the latter wells, it could be said that they were producing crude oils of the same nature at least for 20 months, and the nature of produced oils were kept unchanged in atmospheric condition during the period.The crude oils from such a field as the Yabase whose producing zones are in piles vertically, have a tendency that their aromatics contents are changed unilaterally with the increase of depth. By the use of IR specific values and above the relationship, samples whose sources were unknown, were found to be attributed to the producing zones.This is a rapid and simple and useful method as mentioned above. In addition, many practical uses should be applicable especially when it is not enough for research both in time and in sample amounts.