Title: Small-angle Neutron Scattering (SANS) Characterization of Clay- and Carbonate-rich Shale at Elevated Pressures

Abstract

Unconventional oil and gas from shale formations have emerged as some of the fastest growing energy resources in the United States, providing both cleaner energy to consumers and reducing the nation’s reliance on energy imports. To properly harness these important natural resources, the nanopore structure of associated shales must be fully understood, particularly under hydraulic fracturing conditions, where they are exposed to both overburden compressive and hydrostatic fluid pressures. The current study uses small-angle neutron scattering (SANS) to characterize pore structure, including porosity, pore accessibility, and pore size distribution, in the 1–100 nm regime at elevated pressures for mineralogically distinct clay- and carbonate-rich shales from the Permian Basin. Unlike typical porosity measurement techniques, SANS is uniquely capable of characterizing both open and closed porosity, allowing measurement of how pore accessibility changes with pressure and determination of the size range of accessible versus inaccessible pores. The porosity of the clay-rich shale was 7.7%, compared to 0.51% for the carbonate-rich shale. However, only 2.6% of the nanopores in the carbonate-rich shale were inaccessible to water at 8 kPSI (55.1 MPa) compared to 7.8% for the clay-rich shale. Furthermore, our analyses indicated that the closed pores fall within distinct size ranges, likely correspondingmore » with the chemical nature of the pore host material. These results provide valuable insight into the effects of shale petrophysical properties on hydrocarbon extraction from unconventional reservoirs.« less

Authors:

Neil, Chelsea W.  ^[1];

• Search DOE PAGES for author "Neil, Chelsea W."
• Search DOE PAGES for ORCID "0000-0002-7679-157X"
• Search orcid.org for ORCID "0000-0002-7679-157X"

Hjelm, Rex P. ^[1]; Hawley, Marilyn E. ^[1]; Watkins, Erik B.  ^[1];

• Search DOE PAGES for author "Watkins, Erik B."
• Search DOE PAGES for ORCID "0000-0001-8573-9629"
• Search orcid.org for ORCID "0000-0001-8573-9629"

Cockreham, Cody ^[2]; Wu, Di  ^[3];

• Search DOE PAGES for author "Wu, Di"
• Search DOE PAGES for ORCID "0000-0001-6879-321X"
• Search orcid.org for ORCID "0000-0001-6879-321X"

Mao, Yimin  ^[4];

• Search DOE PAGES for author "Mao, Yimin"
• Search DOE PAGES for ORCID "0000-0002-6240-3791"
• Search orcid.org for ORCID "0000-0002-6240-3791"

Fischer, Timothy B. ^[5]; Stokes, M. Rebecca ^[5]; Xu, Hongwu ^[1]

---

+ Show Author Affiliations

1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Washington State Univ., Pullman, WA (United States)
3. Washington State Univ., Pullman, WA (United States)
4. National Inst. of Standards and Technology (NIST), Gaithersburg, MD (United States). Center for Neutron Research
5. Chevron Energy Technology Co., Houston, TX (United States)

Publication Date:

2020-06-12

Research Org.:

Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)

OSTI Identifier:

1726178

Report Number(s):

LA-UR-19-30857
Journal ID: ISSN 0887-0624

Grant/Contract Number:  

89233218CNA000001; DMR-1508249

Resource Type:

Accepted Manuscript

Journal Name:

Energy and Fuels

Additional Journal Information:

Journal Volume: 34; Journal Issue: 7; Journal ID: ISSN 0887-0624

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; Scattering; shale; porosity; clay