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.
Highlights
Enhanced hydrocarbon recovery techniques are critical for extracting maximum volumes of hydrocarbons from mature fields
Based on the graphs and manual investigation in Petrel, we suggest that ten depressions in the Cromer Knoll Group, overlying depressions in the Mandal Formation, are drape features, whilst the remaining seven depressions are associated with stacked pockmarks that indicate multiple episodes of fluid flow through the same pipe(s)
Detailed investigation of fluid flow features combined with burial history modelling allows us to describe the fluid migration history of the Jæren High, adding to the geological history described by Høiland et al (1993)
Summary
Enhanced hydrocarbon recovery techniques are critical for extracting maximum volumes of hydrocarbons from mature fields. Potential CO2 storage sites may occur adjacently to known producing fields One of such cases is the regionally extensive Permian Rotliegend Group, which is a saline aquifer in areas where hydrocarbons are not found in economic volumes (Wilkinson et al, 2013). Notwithstanding the latter example, the injection of CO2 for combined enhanced hydrocarbon recovery and CCS requires a detailed understanding of geological risks and uncertainties prior to the implementation of such techniques, namely the recognition of potential fluid flow paths through caprocks and the sealing capacity in target storage areas.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
