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 »
- Authors:
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[1]
; [1]
; [2]
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- The Univ. of Texas at Austin, Austin, TX (United States)
- 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); Energy Frontier Research Centers (EFRC) (United States). Center for Frontiers of Subsurface Energy Security (CFSES)
- 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