Spatially resolved 2D Laplace NMR

Within the past decade, 2D Laplace nuclear magnetic resonance (NMR) has been proved to be a powerful method to investigate porous materials. However, it gives information only about integral characteristics of a given sample with regard to pore-size and pore connectivity. It is therefore desirable to combine MRI with 2D-Laplace NMR to generate information about fluid transport within defined areas of a sample. Spatially resolved D-T2 correlation maps were measured for four different samples: glass beads with different bead diameters saturated with water, glass beads filled with oil and water separated by a membrane, a wet mortar sample and glass beads filled with oil and water without a membrane. The information contained in pixels of similar contrast were exploited by spatially resolved D-T2 correlation NMR as a representative of 2D-Laplace NMR. Summation of pixels with similar contrast and low spatial resolution have been chosen to accelerate the measurement time which is inherently long for 2D-Laplace resolved MRI. This method reveals the heterogeneous information of these samples and is expected to be appreciated by the oil industry. Moreover, Gint2D - T2 maps were obtained to study the relationship between pore space and internal gradients in porous media. Three different kinds of samples were measured, which are glass beads with different bead diameters saturated with water, glass beads filled with oil and water, and a wet mortar sample. Two different cases are distinguished: 1) The heterogeneity of internal gradients dominates the heterogeneity of diffusion coefficients, which concerns the first sample. 2) The heterogeneity of diffusion coefficients dominates the heterogeneity of internal gradients, which occurs in the second sample. Only in the first case, the internal gradients can be estimated when assuming a constant diffusion coefficient across the sample. This result delineates the limitations of this assumption. Then the correlation maps of mortar were measured and internal gradient distributions were acquired to explore the utility of this method in reality. Finally, spatially resolved Gint2D - T2 maps were studied at 7 T and 16 T to probe sample heterogeneity