Molecular dynamics and composition of crude oil by low‐field nuclear magnetic resonance

Abstract

Nuclear magnetic resonance (NMR) techniques are widely used to identify pure substances and probe protein dynamics. Oil is a complex mixture composed of hydrocarbons, which have a wide range of molecular size distribution. Previous work show that empirical correlations of relaxation times and diffusion coefficients were found for simple alkane mixtures, and also the shape of the relaxation and diffusion distribution functions are related to the composition of the fluids. The 2D NMR is a promising qualitative evaluation method for oil composition. But uncertainty in the interpretation of crude oil indicated further study was required. In this research, the effect of each composition on relaxation distribution functions is analyzed in detail. We also suggest a new method for prediction of the rotational correlation time distribution of crude oil molecules using low field NMR (LF-NMR) relaxation time distributions. A set of down-hole NMR fluid analysis system is independently designed and developed for fluid measurement. We illustrate this with relaxation-relaxation correlation experiments and rotational correlation time distributions on a series of hydrocarbon mixtures that employ our laboratory-designed downhole NMR fluid analyzer. The LF-NMR is a useful tool for detecting oil composition and monitoring oil property changes. Copyright © 2016 John Wiley & Sons, Ltd.

A novel, sensitive and non‐destructive method for quantitative determination of lipid in live Eriocheir sinensis using low‐field 1H Nuclear magnetic resonance

“…By choosing an appropriate pulse sequence, the signal intensity of samples can be reflected in terms of the T 1 and T 2 relaxation times obtained from Carr‐Purcell‐Meiboom‐Gill (CPMG) and inversion recovery (IR) sequences, respectively (Nakayama et al., 2015). Results of preliminary experiments showed that in terms of performance, T 2 relaxation time was better than that of T 1 relaxation because of “lipid‐water separation” studied in a previous report (Jia et al., 2016). Thus, T 2 measurement has been utilized for further study.…”

“…Low‐field 1 H Nuclear magnetic resonance (LF‐ 1 H NMR) technique is a rapid, non‐destructive, highly reproducible, and sensitive technique (Hazlett et al., 1999; Seton, Hutchison, & Bussell, 1997), and has successfully been applied in quality control of food products such as porcine muscle (Qin, Xu, Zhou, & Wang, 2015; Shao, Deng, Jia, et al., 2016; Shao, Deng, Song, et al., 2016), pork (Shao, Deng, Jia, et al., 2016; Shao, Deng, Song, et al., 2016), salmon (da Silva Carneiro et al., 2016), crude lipid (Barbosa, Sad, Morgan, Figueiras, & Castro, 2016; Jia et al., 2016), egg (Zhao et al., 2016), milk (Salomonsen, Sejersen, Viereck, Ipsen, & Engelsen, 2007), honey (Ribeiro et al., 2014), and cod (Gudjónsdóttir, Arason, & Rustad, 2011). The LF‐ 1 H NMR technique is often employed to investigate the water mobility and/or lipid content of foods because it can measure water or lipid proton relaxation.…”

NMR fluid analyzer applying to petroleum industry

“…Asphalteneeasily aggregates with other molecules to produce a supramolecular structure. This aggregate will slow down molecular motion, which can be detected by measuring T 1 -T 2 distribution (Jia et al 2016). 10 -2 10 -1 10 0 10 1 Signal amplitude 10 -1 10 -2 10 -3 10 -3 10 -2 10 -1 10 0 10 1 (b) Fig.…”

Advances in low-field nuclear magnetic resonance (NMR) technologies applied for characterization of pore space inside rocks: a critical review

“…The first step is to enhance the understanding of multiple relaxation mechanisms related to rock components and pore structures. For instance, prominences including composition diversity, storage, and seepage dominated by nanoscale pores and throats, and coexisting multi-scale pores, make relaxation mechanisms in shales more complex (Washburn and Birdwell 2013;Daigle et al 2014;Jia et al 2016Jia et al , 2017 Washburn and Cheng 2017): (1) Organic matter affects fluid NMR signal, and dipole-dipole coupling between 1 H atoms is the controlling factor. (2) The distribution and compaction of clay influence NMR responses, and clay's type and components will affect the wettability of pores and adsorption of water molecules.…”