Correlation of the inhomogeneous field as a measure of sample heterogeneity.

In this paper we present a method to determine the pore and grain size heterogeneity using a correlation between the transverse relaxation time and the susceptibility induced inhomogeneous magnetic field. By using a CPMG echo train, we are able to correlate T2 with the inhomogeneous internal magnetic field, Bzi. We first introduce a simple simulation to study the correlation between the internal magnetic field gradient, ∣g∣, and Bzi, where this correlation is analogous to the T2–Bzi correlation with horizontal inversion. We then acquire experimental data from two samples, one a simple bead pack, and the other a more complicated sandstone rock core. We find that indeed this method can indicate the presence of pore and grain size heterogeneities in the sample.