Intl. J. of Greenhouse Gas Control: An integrated geological and GIS-based method to assess caprock risk in mature basins proposed for carbon capture and storage

The paper “An integrated geological and GIS-based method to assess caprock risk in mature basins proposed for carbon capture and storage” by Chantelle Roelofse, Tiago M. Alves (3D Seismic Lab, Cardiff University), Joana Gafeira (British Geological Survey) and Kamaldeen O. Omosanya (ARCEx, Oasis Geoconsulting Ltd.) has been published as an open access article in the International Journal of Greenhouse Gas Control.

Highlights

  • An integrated methodology is used to assess fluid flow on the Jæren High.
  • Buried pipes connect deeper reservoirs to shallower units across salt welds.
  • Focused fluid-flow occurred during the Late Jurassic to Early Cretaceous.
  • The observed pipes increases leakage risk for prospective CO2 storage sites.

Abstract:

Subsurface injection of carbon dioxide (CO2) is a technique to enhance oil recovery and so the economic value of depleting fields. It complements carbon capture and storage, which is a key technology to mitigate greenhouse gas emissions. In this work, an integrated method developed by the British Geological Survey and Cardiff University uses high-resolution 3D seismic and borehole data from the Jæren High to analyse potential seal breaches and fluid flow paths in a frontier area of the North Sea, ultimately assessing the risk of a possible carbon capture and storage site. We integrate the spatial analysis of subsurface fluid flow features with borehole and geochemical data to model the burial and thermal history of potential storage sites, estimating the timing of fluid expulsion. On seismic data, fluid pipes connect reservoir intervals of different ages. Spatial analysis reveals clustering of fluid flow features above strata grounded onto deep reservoirs intervals. Our integrated method shows that gas matured from Dinantian coal and migrated up-dip during the Triassic-Jurassic into the lower sandstone reservoir of the Rotliegend Group. The containing seal rock was breached once sufficiently large volumes of gas generated high overpressures in the reservoir. Some of these fluid flow features may still be active conduits, as indicated by bright amplitude anomalies within the pipes. This study shows how integrated analyses may enhance our understanding of fluid-flow pathways, de-risking prospective sites for carbon capture and storage. The method proposed in this work is particularly important to assess the suitability of area with trapped gas pockets and understand tertiary migration in areas proposed for geological storage of CO2.

Keywords

Jæren high, Carbon capture and storage, Seal integrity, Fluid flow, Pockmarks, Gas pipes

Reference: 

Roelofse, C.; Alves, T.M.; Gafeira, J.; Omosanya, K.O. (2019): An integrated geological and GIS-based method to assess caprock risk in mature basins proposed for carbon capture and storage. International Journal of Greenhouse Gas Control, Volume 80, January 2019, Pages 103-122. DOI: 10.1016/j.ijggc.2018.11.007 [intranet]