DETERMINATION OF IRREDUCIBLE WATER CUT-OFF USING TWO DIMENSIONAL NUCLEAR MAGNETIC RESONANCE DATA

摘要

A method for estimating a distribution of pore sizes of a fluid filled rock formation penetrated by a borehole, the method including: processing nuclear magnetic resonance (NMR) data to determine a distribution of diffusion coefficients and a distribution of relaxation time constants for at least one depth in the borehole; plotting the distribution of diffusion coefficients and the distribution of relaxation time constants as a cross-plot for the at least one depth; identifying a water line on the cross-plot, each point on the water line having substantially the same value for the diffusion coefficient; and estimating the distribution of pore sizes from the distribution of relaxation time constants plotted along the water line.