CASP has completed two complementary reports investigating the controls on mudstone seal performance of the Lower Lias Group in the Cleveland Basin, NE England, which provides a direct stratigraphic analogue for seal units within geological carbon storage (CCS) projects across the wider North Sea region.

The first report – Investigating the impact of heterogeneity in mudrock seals, via the multiscale-multiproxy characterisation of the lowermost Lias Group, Cleveland Basin, UK – examines how sedimentological heterogeneity influences seal behaviour across multiple scales within the Early Jurassic Redcar Mudstone Formation. Integrating detailed field logging, petrography, SEM, XRD, handheld XRF and gamma, porosity-permeability and MICP analysis, the study highlights how variations in lithology, depositional facies and sedimentary structures can lead to significant differences in sealing capacity between stratigraphic intervals.

The companion report – Mechanical stratigraphy and fault damage zones impacts on a Lower Jurassic mudrock seal analogue, Cleveland Basin, UK – focuses on fracture networks, fault damage zones and structural controls on seal integrity. Combining structural field data with SEM–EDS and MICP analysis, the study demonstrates that the sealing capacity of mudstones within fault damage zones is significantly reduced. Furthermore, scaling factors for fault damage zone width (W) relative to fault displacement (D) are much higher in this study than reported in the literature, with W>>D for small displacement faults.

Together, these studies reinforce the importance of geological heterogeneity — both sedimentological and structural — in influencing seal performance and underline the value of detailed analogue studies for CCS risking and subsurface model conditioning.

The reports were authored by Colm Pierce, Adam Szulc, Mike Curtis, Michael Flowerdew, Michael Pointon, Niall W. Paterson and Stephen Vincent.

KeyFacts Energy Industry Directory: CASP