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This content will become publicly available on September 22, 2018

Title: CO 2-induced chemo-mechanical alteration in reservoir rocks assessed via batch reaction experiments and scratch testing

Here, the injection of carbon dioxide (CO 2) into geological formations results in a chemical re-equilibration between the mineral assemblage and the pore fluid, with ensuing mineral dissolution and re-precipitation. Hence, target rock formations may exhibit changes of mechanical and petrophysical properties due to CO 2 exposure. We conducted batch reaction experiments with Entrada Sandstone and Summerville Siltstone exposed to de-ionized water and synthetic brine under reservoir pressure (9–10 MPa) and temperature (80°C) for up to four weeks. Samples originate from the Crystal Geyser field site, where a naturally occurring CO 2 seepage alters portions of these geologic formations. We conducted micro-scratch tests on rock samples without alteration, altered under laboratory conditions, and naturally altered over geologic time. Scratch toughness and hardness decrease as a function of exposure time and water salinity up to 52% in the case of Entrada and 87% in the case of Summerville after CO 2-induced alteration in the laboratory. Imaging of altered cores with SEM-EDS and X-ray microCT methods show dissolution of carbonate and silica cements and matrix accompanied by minor dissolution of Fe-oxides, clays, and other silicates. Parallel experiments using powdered samples confirm that dissolution of carbonate and silica are the primary reactions. Themore » batch reaction experiments in the autoclave utilize a high fluid to rock volume ratio and represent an end member of possible alteration associated with CO 2 storage systems. These types of tests serve as a pre-screening tool to identify the susceptibility of rock facies to CO 2-related chemical-mechanical alteration during long-term CO 2 storage.« less
Authors:
ORCiD logo [1] ; ORCiD logo [1] ;  [2] ;  [1] ;  [1] ;  [2]
  1. The Univ. of Texas at Austin, Austin, TX (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Report Number(s):
SAND-2017-9043J
Journal ID: ISSN 2152-3878; 656485
Grant/Contract Number:
AC04-94AL85000; SC0001114
Type:
Accepted Manuscript
Journal Name:
Greenhouse Gases: Science and Technology
Additional Journal Information:
Journal Volume: 8; Journal Issue: 1; Journal ID: ISSN 2152-3878
Publisher:
Society of Chemical Industry, Wiley
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; micromechanics; chemo-mechanical coupling; dissolution; scratch toughness; carbon storage
OSTI Identifier:
1399569
Alternate Identifier(s):
OSTI ID: 1393992