(707c) Molecular Dynamics Simulations of NMR Relaxation: Concepts and Applications to Hydrocarbons and Water in Confined Systems

NMR is extensively used to probe the pore size distribution, fluid distribution, and surface relaxivity of oil and gas reservoirs. However, the interpretation of these NMR-logs still depends on classical models of NMR relaxation that make important assumptions about the nature of the molecules and its interaction with the environment. We have initiated a program to use atomistic molecular dynamics simulations to enhance the understanding and interpretation of NMR relaxation in confined systems of interest in current oil and gas production. In this talk, we will outline the foundational ideas of both NMR and how we can use the atomistic simulations to obtain insights into NMR 1H dipole-dipole and spin-rotation relaxation mechanisms that are of foremost interest in the context of hydrocarbons and water present in unconventional reservoirs. We will discuss our results in modeling the NMR relaxation dynamics and diffusion in bulk methane, the C5-to-C17 normal alkanes, and water. We will also discuss our results on alkane-polymer mixtures that are a mimic for alkanes in kerogen. We conclude by noting some current directions which our team is pursuing.