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| Titel |
CO2 Storage Potential of the Eocene Tay Sandstone, Central North Sea, UK |
| VerfasserIn |
Christopher Gent, John Williams |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250141500
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| Publikation (Nr.) |
 EGU/EGU2017-5021.pdf |
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| Zusammenfassung |
| Carbon Capture and Storage (CCS) is crucial for low-carbon industry, climate mitigation and
a sustainable energy future. The offshore capacity of the UK is substantial and has been
estimated at 78 Gt of CO2 in saline aquifers and hydrocarbon fields. The early-mid Eocene
Tay Sandstone Member of the Central North Sea (CNS) is a submarine-fan system and
potential storage reservoir with a theoretical capacity of 123 Mt of CO2. The Tay
Sandstone comprises of 4 sequences, amalgamating into a fan complex 125km
long and 40 km at a minimum of 1500 m depth striking NW-SE, hosting several
hydrocarbon fields including Gannett A, B, D and Pict. In order to better understand the
storage potential and characteristics, the Tay Sandstone over Quadrant 21 has been
interpreted using log correlation and 3D seismic. Understanding the internal and
external geometry of the sandstone as well as the lateral extent of the unit is essential
when considering CO2 vertical and horizontal fluid flow pathways and storage
security.
3D seismic mapping of a clear mounded feature has revealed the youngest sequence of the
Tay complex; a homogenous sand-rich channel 12 km long, 1.5 km wide and on average 100
m thick. The sandstone has porosity >35%, permeability >5 D and a net to gross of 0.8,
giving a total pore volume of 927x106 m3. The remaining three sequences are a series of
stacked channels and interbedded mudstones which are more quiescent on the seismic,
however, well logs indicate each subsequent sequence reduce in net to gross with age as mud
has a greater influence in the early fan system. Nevertheless, the sandstone properties
remain relatively consistent and are far more laterally extensive than the youngest
sequence.
The Tay Sandstone spatially overlaps several other potential storage sites including the older
Tertiary sandstones of the Cromarty, Forties and Mey Members and deeper Jurassic
reservoirs. This favours the Tay Sandstone to be considered in a secondary or multiple
stacked storage scenario. Principal risks include injection-induced pressure-increase limiting
injectivity, caused by limited connectivity between sand-rich sequences, up-dip migration to
sandstone shelf-facies of the overlying Mousa Formation, or to hydraulically-connected
underlying Tertiary sandstones such as the Forties Member which may in places be in
hydraulic communication. |
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