This project and its resultant report present a comprehensive suite of sedimentological, petrographic, and geochemical data from the Triassic Bunter Sandstone Formation and its equivalents. The study delivers an in-depth regional characterisation of this key reservoir interval across the Southern North Sea (SNS), with direct implications for geological carbon storage.

Through the analysis of 1,002 m of core from nine wells across the UK and Dutch sectors of the SNS, supplemented by 59 petrographic studies, 152 SEM-EDS analyses, 1,669 XRF data points, and a comprehensive compilation of porosity-permeability database, result in a study of unparalleled resolution. This has enabled us to thoroughly test how key sedimentological and diagenetic controls influence Bunter Sandstone Formation reservoir quality. These insights are vital for assessing the injectivity, capacity, and containment security of potential CO₂ storage sites.

A significant contribution of this study is the integration of data from a previously unstudied, near-continuous core through the Triassic succession, enabling the recognition of 15 facies grouped into 11 facies associations and eight depositional environments. This stratigraphic and facies framework underpins a refined understanding of lateral and vertical heterogeneity in reservoir quality. Low porosity and permeability intervals are shown to correlate with mudstone- and siltstone-rich facies associations, which are spatially variable and thus critical for understanding fluid flow and CO₂ plume migration.

Moreover, the study highlights how original sedimentological architecture is further modified by complex diagenetic overprints, including multi-phase cementation (dolomite, calcite, halite) and late-stage dissolution of unstable grains. These features introduce significant spatial variability in reservoir quality, affecting both injectivity and storage permanence. Closely spaced XRF data offer essential compositional constraints at scales compatible with poro-perm datasets, enhancing the predictability of these reservoir characteristics.

The dataset supports not only improved prediction of reservoir quality but also informs dynamic modelling and risk assessment for CO₂ injection and long-term containment. As such, it provides a critical evidence base for screening, site selection, and regulatory assurance in the deployment of geological carbon storage across the Southern North Sea.

Delivery of data

The data are provided in a fully illustrated physical and electronic report of 599 pages including a 382-page appendix of analytical data, nine enclosures, and an accompanying GIS project containing analytical data.

Completed: March 2025

Report details: Reservoir sedimentology, composition and diagenesis of the Bunter Sandstone Formation in the Southern North Sea

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