Chen Joseph J, Hürlimann Martin, Paulsen Jeffrey, Freed Denise, Mandal Soumyajit, Song Yi-Qiao
Schlumberger-Doll Research, One Hampshire Street, Cambridge, MA, 02139 (USA); Department of Chemical and Biomolecular Engineering, University of California, Berkeley, CA, 94703 (USA).
Chemphyschem. 2014 Sep 15;15(13):2676-81. doi: 10.1002/cphc.201402077. Epub 2014 Jun 11.
Crude oils, which are complex mixtures of hydrocarbons, can be characterized by nuclear magnetic resonance diffusion and relaxation methods to yield physical properties and chemical compositions. In particular, the field dependence, or dispersion, of T1 relaxation can be used to investigate the presence and dynamics of asphaltenes, the large molecules primarily responsible for the high viscosity in heavy crudes. However, the T2 relaxation dispersion of crude oils, which provides additional insight when measured alongside T1, has yet to be investigated systematically. Here we present the field dependence of T1-T2 correlations of several crude oils with disparate densities. While asphaltene and resin-containing crude oils exhibit significant T1 dispersion, minimal T2 dispersion is seen in all oils. This contrasting behavior between T1 and T2 cannot result from random molecular motions, and thus, we attribute our dispersion results to highly correlated molecular dynamics in asphaltene-containing crude oils.
原油是碳氢化合物的复杂混合物，可通过核磁共振扩散和弛豫方法进行表征，以得出物理性质和化学组成。特别是，T1弛豫的场依赖性或频散可用于研究沥青质的存在和动力学，沥青质是导致重质原油高粘度的主要大分子。然而，原油的T2弛豫频散（与T1一起测量时可提供更多信息）尚未得到系统研究。在此，我们展示了几种密度不同的原油的T1-T2相关性的场依赖性。含沥青质和树脂的原油表现出显著的T1频散，而所有原油中T2频散都很小。T1和T2之间这种截然不同的行为并非由随机分子运动导致，因此，我们将频散结果归因于含沥青质原油中高度相关的分子动力学。
