A multiproxy-multiscale mudrock catalogue from the Cleveland Basin, UK - analogue analyses to aid GCS seal assessments

A research programme in the Cleveland Basin, UK has sampled and logged more than 600 m of continuous mudrock and intercalated mudrock-evaporite stratigraphy. The studies have investigated both outcrop exposures and continuous borehole core to document heterogeneity in mudrock units and examine the impacts on seal potential for geological carbon storage. The studied successions include the lower Lias Group in outcrop, primarily at Robin Hood’s Bay, and the entire Haisborough Group and lower Lias groups in a nearby onshore core. Here we present the first phase of work examining the lower Lias Group in outcrop (~180 m thick) (Figure 1(A)). Stratigraphic equivalents of the study interval form primary and secondary seals to an expanding group of GCS complexes across the North Sea region. The primary aim of this research was to examine potential links between a comprehensive catalogue of primary (compositional/sedimentological) and secondary (i.e. deformational/diagenetic) heterogeneities with variations in seal potential. The analytical (XRF-XRD, SEM, TOC, MICP, etc.) results have allowed characteristic facies-microfacies, compositional and mineralogical sub-groupings to be established and linked to seal potential (i.e., capacity, reactivity and mechanical strength) using a combination of comparative ranges and PCA analysis. These underpin the construction of relative seal-risk or “vulnerability” maps.