CO2-induced chemo-mechanical alteration in reservoir rocks assessed via batch reaction experiments and scratch testing
- The Univ. of Texas at Austin, Austin, TX (United States)
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Here, the injection of carbon dioxide (CO2) 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 CO2 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 CO2 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 CO2-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. The batch reaction experiments in the autoclave utilize a high fluid to rock volume ratio and represent an end member of possible alteration associated with CO2 storage systems. These types of tests serve as a pre-screening tool to identify the susceptibility of rock facies to CO2-related chemical-mechanical alteration during long-term CO2 storage.
- Research Organization:
- Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Energy Frontier Research Centers (EFRC) (United States). Center for Frontiers of Subsurface Energy Security (CFSES)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
- Grant/Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1399569
- Alternate ID(s):
- OSTI ID: 1393992
- Report Number(s):
- SAND--2017-9043J; {"Journal ID: ISSN 2152-3878",656485}
- Journal Information:
- Greenhouse Gases: Science and Technology, Journal Name: Greenhouse Gases: Science and Technology Journal Issue: 1 Vol. 8; ISSN 2152-3878
- Publisher:
- Society of Chemical Industry, WileyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Chemo-mechanical behavior of clay-rich fault gouges affected by CO 2 -brine-rock interactions : Original Research Article: Chemo-mechanical behavior of clay-rich fault gouges
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journal | December 2018 |
Fracture Propagation in Heterogeneous Porous Media: Pore-Scale Implications of Mineral Dissolution
|
journal | April 2019 |
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