This document is an expanded abstract.

Summary

NMR (Nuclear magnetic resonance) is widely used as a logging tool in reservoir exploration and provides information on pore size distribution, fluid distribution, and insights into wettability. Towards better utilizing NMR log data, it is essential to assess the current models of NMR relaxation. To this end, we explicitly calculate the NMR dipole-dipole relaxation in model hydrocarbons and water for single state points and dipole-dipole and spin-rotation relaxation in methane for a range of state-points spanning the vapor, super-critical, and liquid phases. We can successfully predict 1H NMR T1,2 relaxation and diffusion, but the relaxation behavior siginificantly deviate from those based on classical hard sphere models that are often used to interpret the relaxation behavior.

Introduction

A significant portion of the light hydrocarbons produced from unconventional reservoirs can originate from intra-particle organic matter pores that can be tens of nanometers or less. A better understanding of the hydrocarbon storage properties in nano-confined organic matter pores as a function of the physical and chemical characteristics of the confining matrix could prove helpful in characterizing such reservoirs and guide the way to the development of such unconventional resource plays. We at Rice University are pursuing a multi-pronged approach that integrates molecular statistical mechanical theory, experiments, and molecular simulations to understand the behavior of hydrocarbons in nano-pores and kerogen.

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