Characterising oil and water in porous media using correlations between internal magnetic gradient and transverse relaxation time

Abstract A method for characterising water and oil in a rock core plug using correlations between diffusion decay in internal magnetic gradient and transverse relaxation time ( DG 0 2 - T 2 ) is presented. The method is evaluated at different saturation levels and is compared with the measurement of correlations between diffusion and transverse relaxation time ( D - T 2 ). It is shown how signals from water and oil can be separated based on their difference in diffusion decay in internal gradients. The obtained results show that the impact from heterogeneity in pore geometry and mineralogy on the individual liquids is revealed in more detail in DG 0 2 - T 2 correlations compared to the more established D - T 2 correlations. Measurements of DG 0 2 - T 2 correlations should be included in the toolbox of NMR experiments performed in the laboratory analysis of rock core plugs, and could then potentially lead to more detailed estimations of saturation levels and surface wettability properties.