Chemical resolution in T2-T1 correlations

Abstract

Oil and water fractions have been identified in fluid saturated carbonate rock cores using a novel T₂-T₁-d pulse sequence. The inclusion of the chemical shift dimension d allows T₂-T₁ plots to be generated independently for the oil and water. The T₂-T₁-d pulse sequence utilises a “double-shot” T₁ measurement that provides free induction decays (FIDs) as a function of both relaxation times for suitably broad line samples. The T₂-T₁-d data set is acquired in the same experimental time as a conventional T₁-T₂ measurement (without chemical resolution) of equivalent data density. Here we demonstrate that different behaviour can be observed between the oil and water fractions in water wet and preferentially oil wet cores, and that saturation states can be determined. This technique could provide a quantitative NMR measure of wettability.