(739e) NMR Relaxation from Molecular Simulations: Study on Bulk Hydrocarbons and Water

Nuclear magnetic resonance(NMR) relaxometry is used to get properties like pore size distribution, fluid distribution, and wettability in reservoir exploration. However, the interpretation of the NMR log data relies on classical models, that make important assumptions on the nature of the fluid and environment. Here we use molecular dynamics and NMR theories to seek a fresh perspective on interpreting relaxation mechanisms. In this talk, I will discuss the interpretations of dipole-dipole and spin rotation relaxation mechanisms in bulk systems. The simulated relaxation and diffusivity are in excellent agreement with experiments. However the results are consistent with the classical models of relaxation that assumes particles are spherical and interactions are isotropic. I will further discuss the effects of internal motions and molecular geometry on relaxation. Interestingly the relaxation behavior of neopentane closely conforms to classical behavior. Time permitting, I will also discuss our ongoing work examining NMR relaxation in alkane-polymer mixtures.