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Title: Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.

Abstract

Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper andmore » lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. Results from this study, combined with high-resolution TEM imaging, provide insight into the differences in volume and geometry of porosity between these various mudstones.« less

Authors:
 [1];  [1];  [1]; ; ;  [2]
  1. Colorado School of Mines
  2. Oak Ridge National Laboratory
Publication Date:
Research Org.:
Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1030296
Report Number(s):
SAND2010-7711C
TRN: US1105948
DOE Contract Number:  
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the 2010 Gelological Socity of Amerai (GSA) Annual Meeting held October 31-November 3, 2010 in Denver, CO.
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; AQUIFERS; CARBON; CARBON SEQUESTRATION; CLAYS; DISTRIBUTION; FLUID FLOW; FORECASTING; GEOMETRY; NEUTRONS; POROSITY; SCATTERING; SCATTERING LENGTHS; SHALES; SHAPE; TRANSPORT; TRAPPING

Citation Formats

McCray, John, Navarre-Sitchler, Alexis, Mouzakis, Katherine, Heath, Jason E, Dewers, Thomas A, and Rother, Gernot. Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.. United States: N. p., 2010. Web.
McCray, John, Navarre-Sitchler, Alexis, Mouzakis, Katherine, Heath, Jason E, Dewers, Thomas A, & Rother, Gernot. Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.. United States.
McCray, John, Navarre-Sitchler, Alexis, Mouzakis, Katherine, Heath, Jason E, Dewers, Thomas A, and Rother, Gernot. Mon . "Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.". United States.
@article{osti_1030296,
title = {Initial characterization of mudstone nanoporosity with small angle neutron scattering using caprocks from carbon sequestration sites.},
author = {McCray, John and Navarre-Sitchler, Alexis and Mouzakis, Katherine and Heath, Jason E and Dewers, Thomas A and Rother, Gernot},
abstractNote = {Geological carbon sequestration relies on the principle that CO{sub 2} injected deep into the subsurface is unable to leak to the atmosphere. Structural trapping by a relatively impermeable caprock (often mudstone such as a shale) is the main trapping mechanism that is currently relied on for the first hundreds of years. Many of the pores of the caprock are of micrometer to nanometer scale. However, the distribution, geometry and volume of porosity at these scales are poorly characterized. Differences in pore shape and size can cause variation in capillary properties and fluid transport resulting in fluid pathways with different capillary entry pressures in the same sample. Prediction of pore network properties for distinct geologic environments would result in significant advancement in our ability to model subsurface fluid flow. Specifically, prediction of fluid flow through caprocks of geologic CO{sub 2} sequestration reservoirs is a critical step in evaluating the risk of leakage to overlying aquifers. The micro- and nanoporosity was analyzed in four mudstones using small angle neutron scattering (SANS). These mudstones are caprocks of formations that are currently under study or being used for carbon sequestration projects and include the Marine Tuscaloosa Group, the Lower Tuscaloosa Group, the upper and lower shale members of the Kirtland Formation, and the Pennsylvanian Gothic shale. Total organic carbon varies from <0.3% to 4% by weight. Expandable clay contents range from 10% to {approx}40% in the Gothic shale and Kirtland Formation, respectively. Neutrons effectively scatter from interfaces between materials with differing scattering length density (i.e. minerals and pores). The intensity of scattered neutrons, I(Q), where Q is the scattering vector, gives information about the volume of pores and their arrangement in the sample. The slope of the scattering data when plotted as log I(Q) vs. log Q provides information about the fractality or geometry of the pore network. Results from this study, combined with high-resolution TEM imaging, provide insight into the differences in volume and geometry of porosity between these various mudstones.},
doi = {},
url = {https://www.osti.gov/biblio/1030296}, journal = {},
number = ,
volume = ,
place = {United States},
year = {2010},
month = {11}
}

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