Re-Evaluation of the Forth Approaches Basin: the Debatable Hydrocarbon Prospectivity and the Storage Potential

Summary The UK offshore Forth Approaches Basin has long since been explored as a prospective petroleum system; the few exploration wells failed to point towards an economically viable asset, and hence, the basin was downgraded for further exploration. In this study, this basin is further explored, both in terms of its local hydrocarbon prospectivity and storage potential, using publicly available data. The petroleum system elements of the most prospective play (Scremerston) were assessed based on formation properties and gross depositional environment mapping, source rock maturity modelling and common risk segment mapping. Also, the basin’s carbon storage potential was assessed with respect to its capacity, reservoir and trap quality and seal integrity. Our results suggest that only deeper parts of the depocenter could have generated and stratigraphically trapped vapour hydrocarbons, yet the exact depths of this upper-limit threshold in the Carboniferous depocenter have to be delineated. On the other hand, the Upper-Carboniferous and Middle-Permian reservoir strata, hosting a low-salinity aquifer, illustrate significant storage capacity (roughly 700 Mt for the Worst-Case scenario) and sealing efficiency (through stratigraphic and residual trapping), whereas its proximity to the UK major industrial emitters adds to its applicability.