Title: Impact of Pore Fluid Chemistry on Fine-Grained Sediment Fabric and Compressibility

Abstract

Fines, defined here as grains or particles, less than 75µm in diameter, exist nearly ubiquitously in natural sediment, even those classified as coarse. Macroscopic sediment properties, such as compressibility, which relates applied effective stress to the resulting sediment deformation, depend on the fabric of fines. Unlike coarse grains, fines have sizes and masses small enough to be more strongly influenced by electrical interparticle forces than by gravity. These electrical forces acting through pore fluids are influenced by pore-fluid chemistry changes. Macroscopic property dependence on pore-fluid chemistry must be accounted for in sediment studies involving subsurface flow and sediment stability analyses, as well as in engineered flow situations such as groundwater pollutant remediation, hydrocarbon migration or other energy resource extraction applications. This study demonstrates how the liquid-limit-based electrical sensitivity index can be used to predict sediment compressibility changes due to pore-fluid chemistry changes. Laboratory tests of electrical sensitivity, sedimentation and compressibility illustrate mechanisms linking micro- and macro-scale processes for selected pure, endmember fines. In conclusion, a specific application considered here is methane extraction via depressurization of gas hydrate-bearing sediment, which causes a dramatic pore-water salinity drop concurrent with sediment being compressed by the imposed effective stress increase.

Authors:

Jang, Junbong  ^[1];

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• Search DOE PAGES for ORCID "0000-0001-5500-7558"
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Cao, Shuang C. ^[2]; Stern, Laura A. ^[3]; Jung, Jongwon ^[4]; Waite, William F.  ^[1]

• Search DOE PAGES for author "Waite, William F."
• Search DOE PAGES for ORCID "0000-0002-9436-4109"
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+ Show Author Affiliations

1. U.S. Geological Survey, Woods Hole MA (United States)
2. Louisiana State Univ., Baton Rouge, LA (United States). Civil and Environmental Engineering
3. U.S. Geological Survey, Menlo Park, CA (United States)
4. Louisiana State Univ., Baton Rouge, LA (United States). Civil and Environmental Engineering; Chungbuk National Univ., Chungbuk (South Korea). School of Civil Engineering

Publication Date:

2018-06-26

Research Org.:

Louisiana State Univ., Baton Rouge, LA (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE)

OSTI Identifier:

1460770

Alternate Identifier(s):

OSTI ID: 1460600

Grant/Contract Number:  

FE0028966; FE0026166

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Geophysical Research. Solid Earth

Additional Journal Information:

Journal Volume: 123; Journal Issue: 7; Journal ID: ISSN 2169-9313

Publisher:

American Geophysical Union

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; fine‐grained sediment fabric; electrical sensitivity; pore‐fluid chemistry; sedimentation; compressibility; methane hydrate