Quantification of Organic Porosity and Water Accessibility in Marcellus Shale Using Neutron Scattering

Xin Gu, David F.R. Mildner, David R. Cole, Gernot Rother, Rudy Slingerland, Susan L. Brantley

Research output: Contribution to journalArticlepeer-review

104 Scopus citations

Abstract

Pores within organic matter (OM) are a significant contributor to the total pore system in gas shales. These pores contribute most of the storage capacity in gas shales. Here we present a novel approach to characterize the OM pore structure (including the porosity, specific surface area, pore size distribution, and water accessibility) in Marcellus shale. By using ultrasmall and small-angle neutron scattering, and by exploiting the contrast matching of the shale matrix with suitable mixtures of deuterated and protonated water, both total and water-accessible porosity were measured on centimeter-sized samples from two boreholes from the nanometer to micrometer scale with good statistical coverage. Samples were also measured after combustion at 450 °C. Analysis of scattering data from these procedures allowed quantification of OM porosity and water accessibility. OM hosts 24-47% of the total porosity for both organic-rich and -poor samples. This porosity occupies as much as 29% of the OM volume. In contrast to the current paradigm in the literature that OM porosity is organophilic and therefore not likely to contain water, our results demonstrate that OM pores with widths >20 nm exhibit the characteristics of water accessibility. Our approach reveals the complex structure and wetting behavior of the OM porosity at scales that are hard to interrogate using other techniques.

Original languageEnglish
Pages (from-to)4438-4449
Number of pages12
JournalEnergy and Fuels
Volume30
Issue number6
DOIs
StatePublished - Jun 16 2016

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