METHOD FOR DETERMINING GROUP COMPOSITION OF OIL PRODUCTS USING NMR RELAXOMETRY Russian patent published in 2024 - IPC G01N24/08 

FIELD: physics.

SUBSTANCE: use for determination of group composition of oil products using NMR relaxometry. Substance of the invention consists in the fact that three test tubes are taken with control samples of known weight, which are 25%, 50% and 75% aqueous solutions of deuterium oxide D₂O, and use them for performing single calibration of gain of NMR relaxometer with frequency of proton resonance of not less than 20 MHz so that unit of signal amplitude is equal to value of signal from 1 mg of distilled water, which enables to exclude repeated measurement of the reference sample during each measurement of the analysed sample; then, to obtain a representative homogeneous sample, the container with the oil product sample is held at temperature of 70±0.2 °C for at least 30 minutes to ensure melting of paraffins; then the contents of the container with the sample are mixed with spatula for 2–3 minutes; further, the prepared homogenised sample is placed in a fluoroplastic container to height of 15 mm, with the possibility of providing maximum filling in the resonance region of the measuring coil of the NMR relaxometer; then the test tube with the sample is thermostated for at least 15 minutes at temperature of 70±0.2 °C; then performing NMR relaxometer adjustment, wherein for measuring two free induction decay signals and an envelope of echo signals in a Carr-Purcell-Meiboom-Gill series, performed sequentially on a NMR relaxometer, performing measurement parameters input, namely for measurement of free induction decay signal: recording frequency — 1 MHz, recording time — 6 ms, number of accumulations — 9, repetition time — 2 s; for the envelope of echo signals in the Carr-Purcell-Meiboom-Gill series: time between echoes — 50 mcs, number of echoes — 6,000, number of accumulations — 9, repetition time — 2 s; then container with prepared sample is placed in NMR relaxometer and measurement process is started, as a result of which a free induction decay signal with a minimum "dead time" of 10 mcs and an envelope of the echo signals in the Carr-Purcell-Meiboom-Gill series are recorded; then performing mathematical processing of results.

EFFECT: providing the possibility of creating an easy-to-implement, fast and efficient method of analysing group composition of oil products.

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