A Tale of Two Equations: Low-Field Nuclear Magnetic Resonance Contributions to Crude Oil Reservoir Characterization by Rock Core Analysis

What is it about?

Hydrocarbon reservoirs remain a cornerstone of the global energy landscape; precise reservoir characterization is essential to evaluate the viability of crude oil production. Addressing the challenges inherent in low-permeability, low-porosity formations and near-wellbore environments is critical for maintaining sustainable production. Due to the heterogeneity of deep reservoir cores, non-destructive analytical methods are required for sample reuse. Nuclear Magnetic Resonance (NMR) techniques - specifically low-field (LF) NMR and Magnetic Resonance Imaging (MRI) - have emerged as essential tools for the spatial characterization of pore networks. While these methods are well-established for determining porosity and permeability in sandstones, the characterization of carbonates is more complex due to their intricate chemistry, multi-scale geological features, and geo-mechanical properties. This review article synthesizes the theoretical framework and practical applications of NMR for determining the petrophysical properties of sandstone and carbonate rocks, including porosity, permeability, and fluid saturations. We provide a concise historical overview and a technical evaluation of the primary equations used in LF-NMR data inversion. We examine recent advancements in LF-NMR and MRI applications, identify persistent challenges and future perspectives, and summarize key lessons learned from the recent literature. Hence, this review provides a comprehensive roadmap for applying magnetic resonance to rock core analysis.

Featured Image