title: Two-dimensional diffusion time correlation experiment using a single direction gradient.
abstract: The time dependence of the diffusion coefficient is a well known property of porous media and commonly obtained by pulsed field gradient (PFG) NMR. In practical materials, its analysis can be complicated by the presence of a broad pore size distribution and multiple fluid phases with different diffusion coefficients. We propose a two-dimensional Diffusion Time Correlation experiment (DTC), which utilizes the double-PFG with a single-direction gradient to yield a two-dimensional correlation function of the diffusion coefficient for two different diffusion times. This correlation map separates out restricted diffusion from the bulk diffusion process and we demonstrate this on a plant and bulk water sample. In its development, we show that the d-PFG should then be thought of as correlating two apparent diffusion coefficients measured by two overlapping gradient waveforms.
authors.affiliation: Schlumberger-Doll Research Cambridge, MA 02139, United States. Electronic address: jpaulsen2@slb.com.
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Paulsen
authors.affiliation: Schlumberger-Doll Research Cambridge, MA 02139, United States.
authors.forename: Yi-Qiao
authors.initials: YQ
authors.lastname: Song
keywords: Diffusion–diffusion correlation; Porous media; Restricted diffusion; d-PFG