Geological evaluation of suprasalt carbon storage opportunities in the Silverpit Basin, United Kingdom southern North Sea

• Published in: AAPG bulletin Vol. 106; no. 9; pp. 1791 - 1825
• Main Authors: Hollinsworth, A. D, de Jonge-Anderson, I, Underhill, J. R, Jamieson, R. J
• Format: Journal Article
• Language: English
• Published: American Association of Petroleum Geologists 01-09-2022
• Subjects: Anglo-Polish Trough; applied (geophysical surveys & methods); Atlantic Ocean; Bacton Group; Bunter; carbon dioxide; carbon sequestration; dikes; Engineering geology; England; Europe; faults; geophysical methods; geophysical profiles; geophysical surveys; Geophysics; Great Britain; Haisborough Group; intrusions; Lower Permian; Lower Triassic; Mesozoic; North Atlantic; North Sea; Paleozoic; Penarth Group; Permian; porosity; reservoir properties; Rhaetian; Rotliegendes; salt tectonics; seismic methods; seismic profiles; Silverpit Basin; storage; structural controls; surveys; tectonics; Triassic; United Kingdom; Upper Permian; Upper Triassic; Western Europe; Zechstein
• ISSN: 0149-1423
• DOI: 10.1306/03232221119

Geological CO2 storage presents an opportunity for industrial innovation and revitalization by offsetting greenhouse gas emissions. Its deployment can help countries meet national "net zero" targets and address the multifaceted challenges of the climate crisis. Being a well-studied, data-rich, mature basin facing major industrial clusters located in northeastern England, the United Kingdom Southern North Sea has the potential to be a significant geological CO2 storage location. Numerous well-defined, periclinal and domal closures that host Lower Triassic Bunter Sandstone Formation reservoirs, sealed by Middle Triassic mudstones and evaporites, are prime storage targets. We present a critical geological evaluation of the Bunter Sandstone Formation closures in the Silverpit Basin of the Southern North Sea, based on closure depth, container size, and seal integrity. Integration of seismic well ties, the seismic interpretation of key stratigraphic horizons and their depth conversion using a seven-layer velocity model provides the basis for a new theoretical CO2 storage capacity model that incorporates volumetric calculations and CO2 phase and density based on depth and well-calibrated temperature data. The results enable the carbon storage potential of 11 closures to be risked, compared, and ranked. Three large (>1200 million tons of CO2 [MtCO2]) and six modest (8-300 MtCO2) Bunter Sandstone-bearing dry closures and two depleted gas fields have been identified, forming a geological CO2 storage portfolio for the Silverpit Basin. A further three closures were discounted due to shallow crestal depths and geological (fault-related) integrity concerns. This initial ranking process paves the way for site-specific studies that incorporate geological heterogeneity and nontechnical risks to geological CO2 storage, including well integrity concerns.