Field-cycling NMR Relaxometry: Instrumentation, Model Theories and Applications
Chapter 18: Probing the Dynamics of Petroleum Fluids in Bulk and Confinement by Fast Field-cycling Relaxometry
Published:11 Oct 2018
Some experiments and theoretical models showing how fast field-cycling relaxometry allows the probing of surface correlation times, diffusion coefficients and dynamic surface affinity (NMR wettability) of petroleum fluids (oil and brine-water) in bulk and confinements are presented. The main focus is on the interpretation of nuclear magnetic relaxation dispersion (NMRD) of the longitudinal relaxation rates 1/T1(ω0) for measuring hydrocarbons dynamics in proximity of asphaltene nano-aggregates and macro-aggregates in heavy crude oils in presence of different concentrations of asphaltenes. NMRD profiles also give new information on the dynamic surface affinity or NMR wettability of petroleum fluids (brine and oil) embedded in the complex organic and mineral microstructures of shale oil rocks. This is of particular importance for interpreting T1, T2, T1−T2 and D−T2 correlation spectra that could be obtained down-hole, thus providing a valuable tool for investigating in situ the molecular dynamics of petroleum fluids.