Pores in marcellus shale

A neutron scattering and FIB-SEM study

Xin Gu, David R. Cole, Gernot Rother, David F.R. Mildner, Susan Louise Brantley

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

The production of natural gas has become increasingly important in the United States because of the development of hydraulic fracturing techniques, which significantly increase the permeability and fracture network of black shales. The pore structure of shale is a controlling factor for hydrocarbon storage and gas migration. In this work, we investigated the porosity of the Union Springs (Shamokin) Member of the Marcellus Formation from a core drilled in Centre County, PA, USA, using ultrasmall-angle neutron scattering (USANS), small-angle neutron scattering (SANS), focused ion beam scanning electron microscopy (FIB-SEM), and nitrogen gas adsorption. The scattering of neutrons by Marcellus shale depends on the sample orientation: for thin sections cut in the plane of bedding, the scattering pattern is isotropic, while for thin sections cut perpendicular to the bedding, the scattering pattern is anisotropic. The FIB-SEM observations allow attribution of the anisotropic scattering patterns to elongated pores predominantly associated with clay. The apparent porosities calculated from scattering data from the bedding plane sections are lower than those calculated from sections cut perpendicular to the bedding. A preliminary method for estimating the total porosity from the measurements made on the two orientations is presented. This method is in good agreement with nitrogen adsorption for both porosity and specific surface area measurements. Neutron scattering combined with FIB-SEM reveals that the dominant nanosized pores in organic-poor, clay-rich shale samples are water-accessible sheetlike pores within clay aggregates. In contrast, bubblelike organophilic pores in kerogen dominate organic-rich samples. Developing a better understanding of the distribution of the water-accessible pores will promote more accurate models of water-mineral interactions during hydrofracturing.

Original languageEnglish (US)
Pages (from-to)1295-1308
Number of pages14
JournalEnergy and Fuels
Volume29
Issue number3
DOIs
StatePublished - Jan 1 2015

Fingerprint

Focused ion beams
Shale
Neutron scattering
Scattering
Porosity
Scanning electron microscopy
Clay
Nitrogen
Kerogen
Mineral Waters
Water
Gas adsorption
Hydraulic fracturing
Pore structure
Hydrocarbons
Specific surface area
Natural gas
Neutrons
Minerals
Gases

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Fuel Technology
  • Energy Engineering and Power Technology

Cite this

Gu, Xin ; Cole, David R. ; Rother, Gernot ; Mildner, David F.R. ; Brantley, Susan Louise. / Pores in marcellus shale : A neutron scattering and FIB-SEM study. In: Energy and Fuels. 2015 ; Vol. 29, No. 3. pp. 1295-1308.
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Pores in marcellus shale : A neutron scattering and FIB-SEM study. / Gu, Xin; Cole, David R.; Rother, Gernot; Mildner, David F.R.; Brantley, Susan Louise.

In: Energy and Fuels, Vol. 29, No. 3, 01.01.2015, p. 1295-1308.

Research output: Contribution to journalArticle

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