skip to main content


This content will become publicly available on July 18, 2017

Title: Experimental Study of Porosity Changes in Shale Caprocks Exposed to Carbon Dioxide-Saturated Brine II: Insights from Aqueous Geochemistry

Laboratory experiments evaluated two shale caprock formations, the Gothic Shale and Marine Tuscaloosa Formation, at conditions relevant to carbon dioxide (CO2) sequestration. Both rocks were exposed to CO2-saturated brines at 160°C and 15 MPa for ~45 days. Baseline experiments for both rocks were pressurized with argon to 15 MPa for ~35 days. Varying concentrations of iron, aqueous silica, sulfate, and initial pH decreases coincide with enhanced carbonate and silicate dissolution due to reaction between CO2-saturated brine and shale. Saturation indices were calculated and activity diagrams were constructed to gain insights into sulfate, silicate, and carbonate mineral stabilities. We found that upon exposure to CO2-saturated brines, the Marine Tuscaloosa Formation appeared to be more reactive than the Gothic Shale. Evolution of aqueous geochemistry in the experiments is consistent with mineral precipitation and dissolution reactions that affect porosity. Finally, this study highlights the importance of tracking fluid chemistry to clarify downhole physicochemical responses to CO2 injection and subsequent changes in sealing capacity in CO2 storage and utilization projects.
 [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [4] ;  [5] ;  [6] ;  [6] ;  [7]
  1. Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology and Geophysics
  2. Univ. of Wyoming, Laramie, WY (United States). Dept. of Geology and Geophysics; Univ. of Wyoming, Laramie, WY (United States). School of Energy Resources
  3. Colorado School of Mines, Golden, CO (United States). Dept. of Geology and Geological Engineering and Hydrologic Sciences and Engineering Program
  4. Univ. of Wyoming, Laramie, WY (United States). Dept. of Chemical Engineering
  5. Colorado School of Mines, Golden, CO (United States). Civil and Environmental Engineering
  6. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division
  7. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Dept. of Geomechanics
Publication Date:
Grant/Contract Number:
Accepted Manuscript
Journal Name:
Environmental Engineering Science
Additional Journal Information:
Journal Name: Environmental Engineering Science; Journal ID: ISSN 1092-8758
Mary Ann Liebert, Inc.
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
58 GEOSCIENCES; geologic carbon storage; caprock; porosity
OSTI Identifier: