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Causes of underpressure in natural CO (sub 2) reservoirs and implications for geological storage

Daria Akhbari and Marc A. Hesse
Causes of underpressure in natural CO (sub 2) reservoirs and implications for geological storage
Geology (Boulder) (January 2017) 45 (1): 47-50


Geological carbon storage has the potential to reduce anthropogenic carbon dioxide emissions, if large volumes can be injected and securely retained. Storage capacity is limited by regional pressure buildup in the subsurface. However, natural CO (sub 2) reservoirs in the United States are commonly underpressured, suggesting that natural processes reduce the pressure buildup over time and increase storage security. To identify these processes, we studied Bravo Dome natural CO (sub 2) reservoir (New Mexico, USA), where the gas pressure is up to 6.4 MPa below the hydrostatic pressure, i.e., less than 30% of the expected pressure. Here, we show that the dissolution of CO (sub 2) into the brine reduces the pressure by 1.02 + or - 0.08 MPa, because Bravo Dome is isolated from the ambient hydrologic system. This challenges the assumption that the successful long-term storage of CO (sub 2) is limited to open geological formations. We also show that the formation containing the reservoir was already 2.85 + or - 2.02 MPa underpressured before CO (sub 2) emplacement. This is likely due to the overlying evaporite layer, which prevents recharge. Similar underpressured formations below regional evaporites are widespread in the midcontinent of the United States. This suggests the existence of significant storage capacities with properties similar to Bravo Dome, which has contained large volumes of CO (sub 2) over millennial time scales.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 45
Serial Issue: 1
Title: Causes of underpressure in natural CO (sub 2) reservoirs and implications for geological storage
Affiliation: University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States
Pages: 47-50
Published: 201701
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2017-006054
Categories: Engineering geology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2017012
Illustration Description: illus. incl. geol. sketch map
N31°30'00" - N37°00'00", W109°04'60" - W103°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201705
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