Core Analysis Supports Borehole NMR Applications

Abstract

In most cases, reservoir properties cannot be precisely detected and evaluated via formation-scale investigation through downhole NMR logging measurements alone, and need to be delicately characterized by performing NMR rock core analysis techniques. NMR has continued its development as a unique tool for investigating rock cores to unravel the morphological features and hierarchy of interactions with fluids confined in its pore space. The relaxation time/diffusion coefficient distributions, as well as their multidimensional correlation maps, are routinely utilized to characterize pore size, wetting state, fluid types, and fluid components, quantify individual fluid phase saturations, etc. Meanwhile, MRI was introduced to provide insight into the presence of fluid bearing in the pore network, to provide a permeability profile and reflect the heterogeneity. In this chapter, the establishment and application of NMR well logging models for interpretation by NMR core analysis and particular issues, like pore structure heterogeneity, permeability, wettability index, viscosity prediction, crude oil dynamics and organic matter characterization, are demonstrated.