Probing multi-dynamics of crude oils by high field 2D NMR DOSY and relaxometry

Abstract We propose using a set of non-invasive multiscale NMR techniques for probing the structure and dynamics of bulk and confined crude oils with and without asphaltene. High field NMR spectroscopy identifies the proton species. 2 D NMR DOSY spectra for bulk crude oils in presence or absence of asphaltene favor an interpretation of two populations of hydrocarbon aliphatic chains in two environments. In the presence of asphaltene, an analysis of the distributions of longitudinal relaxation time, T 1 , in terms of a bimodal log-normal distribution, confirms the two environments clearly evidenced by varying the Larmor frequency. The remarkable features of the nuclear magnetic relaxation dispersion ( NMRD ) of 〈1/ T 1 〉 for bulk and confined crude oils with and without asphaltene have been interpreted with an original model of intermittent surface dynamics of proton species at proximity of the surface of asphaltene nanoaggregates and bulk dynamics in between the clusters of these nanoaggregates.