A regional CO 2 containment assessment of the northern Utsira Formation seal and overburden, northern North Sea

Research output: Contribution to journalArticlepeer-review

  • Authors:
  • Christopher Lloyd
  • Mads Huuse
  • Bonita J. Barrett
  • Margaret A. Stewart
  • Andrew M. W. Newton

Abstract

Upscaling Carbon Capture and Storage requires identification of suitable storage sites, with robust reservoir seals. The Utsira Formation in the northern North Sea has been flagged as a target for further storage. However, there are no regional studies of seal variability addressing heterogeneities that could facilitate seal bypass. This study aims to: 1) identify, assess and map the elements that promote or restrict fluid migration, 2) develop a matrix to regionally map containment confidence (CC), and 3) rank the different areas for CO2 containment across the Utsira Formation.
The seal and overburden were mapped using a high-resolution, pre-stack depth-migrated 3D broadband seismic reflection dataset and 141 exploration wells. Seal geometry, sandstone presence and sandstone connectivity in the seal and overburden were assigned relative CC scores, which were summed to map overall containment confidence of the Utsira Fm. Indicators for shallow gas and migration were mapped and correlated to the other elements.
Areas with the lowest CC are in the west of the Utsira Fm. Here, sandstones within the Seal Interval are connected through the overburden via sandy submarine fans. In the southeast, dipping stratigraphy downlaps onto the Utsira Fm., increasing the potential for connection with glacially-derived channel-lobe systems in the overburden. The areas with the highest CC are the central and northeast parts of the Utsira Fm., where the Seal Interval is mudstone-dominated and parallel-to-reservoir, and channel-lobe systems identified in the Overburden Interval are disconnected from the reservoir. This area coincides with a thick depocentre of the northern Utsira Fm. These results can be used to inform CO2 storage site selection and constrain future CO2 plume simulation analyses for the Utsira Fm. The CC matrix outlined here can also be adapted and applied to regionally assess the containment of other potential CO2 storage reservoirs in any setting.

Bibliographical metadata

Original languageEnglish
Pages (from-to)1985-2017
Number of pages33
JournalBasin Research
Volume33
Issue number3
Early online date23 Jan 2021
DOIs
Publication statusPublished - 1 Jun 2021