Numerical Simulations of NMR Responses for Improved Interpretations of NMR Measurements in Reservoir Rocks

Abstract We reconstruct the three-dimensional (3D) microstructure of Fontainebleau sandstone samples of different porosities by a process-based reconstruction method. Permeabilities of the reconstructed media are computed by solving the Stokes equations, while the formation factors are computed by solving a Laplacian equation. Nuclear Magnetic Resonance (NMR) responses are determined by a random walk simulation, and the results are compared with experimental data. Permeabilities estimated from commonly used NMR correlations are compared with the computed permeabilities. The comparison shows that the accuracy of the NMR-derived permeabilities can be improved significantly by accounting for tortuosity effects and variations in surface relaxivity.