Probing Dynamics and Interaction of Maltenes with Asphaltene Aggregates in Crude Oils by Multiscale NMR

Asphaltenes cause many problems in crude oil transportation, refinery, and production. A clear understanding of asphaltene behavior in crude oils is thus crucial for improving crude oil production. Here, we used noninvasive multiscale NMR techniques such as low field NMR 2D D–T2, T1–T2, nuclear magnetic relaxation dispersion (NMRD) techniques as well as high field two-dimensional (2D) NMR DOSY for probing the dynamics and interaction of maltenes with asphaltene aggregates in crude oil. We prepared different asphaltene concentrations ranging between 0 wt % (pure maltenes) and 9 wt % (native crude oil) by using a dilution procedure that maintains the asphaltene aggregates structure initially present in native crude oil. We showed by multiscale NMR techniques that changing asphaltene concentration induces a drastic modification of hydrocarbon dynamics. In native crude oil, we observe anomalous relation between the diffusion coefficient (D) and the transverse relaxation time (T2) that we can reproduce theoret...