Precipitation/dissolution of calcium carbonate in wellbore cement and its implications for the seal integrity of abandoned wells
Wellbore integrity of abandoned wells is of high priority for ensuring the containment of sequestered CO 2 . Carbonic acid formed when injected CO 2 mixes with subsurface brines has the potential to damage well cement so as to compromise the seal integrity of the wellbore. Bench-scale experiments re...
| Main Authors: | , , |
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| Language: | unknown |
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2021
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| Subjects: | |
| Online Access: | http://www.osti.gov/servlets/purl/1326359 https://www.osti.gov/biblio/1326359 |
| Summary: | Wellbore integrity of abandoned wells is of high priority for ensuring the containment of sequestered CO 2 . Carbonic acid formed when injected CO 2 mixes with subsurface brines has the potential to damage well cement so as to compromise the seal integrity of the wellbore. Bench-scale experiments reported in the literature indicate that the well cement reaction rates are initially fast enough to constitute a potential threat to wellbore integrity. However, it has also been suggested that the formation of calcium carbonate within the cement effectively arrests the acid attack by forming a passivation layer (so called “self -sealing”) that prevents further leaching of cement minerals. As a result, a broader theoretical context is presented here that delineates brine composition regimes that will instigate self-sealing in cement during carbonic acid attack. |
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