Carboniferous and Devonian petroleum systems of the UKCS:
An overview of regional structure and stratigraphy from the 21^st Century Exploration Roadmap Palaeozoic Project

With Dr Alison Monaghan (Geologist and Project Leader), British Geological Survey

The 21^st Century Exploration Roadmap Palaeozoic Project has addressed challenges identified in the Wood Review including provision of consistent, regional digital datasets, stimulating exploration of new Carboniferous and Devonian plays across the UKCS and encouraging collaboration across sectors. A large volume of seismic, well and gravity interpretations have been combined with organic geochemistry, petrophysical and basin modelling results to provide Carboniferous and Devonian petroleum systems analyses in and around the Mid North Sea High, Central North Sea, Orcadian Basin and Irish Sea. The full results of this joint industry project are currently confidential and thus this talk will give a general overview of the work done and the significance of new understanding of regional structure and the stratigraphy of the Palaeozoic intervals. 

Previous tectonic maps are largely blank over areas on and around the Mid North Sea High and north of the Moray Firth. The regional seismic mapping undertaken has defined a series of Palaeozoic basins of varying age, size and thickness. A complex picture of variably-oriented Devonian and Carboniferous normal, strike-slip and reversed faults emerges on an inherited basement fabric, with numerous granite-cored blocks. Correlations to onshore UK are clear.

Integrated regional seismic mapping and well re-interpretations have increased the interpreted spatial extent of many Carboniferous and Devonian potential source and reservoir intervals e.g. Visean – Namurian coal-bearing sequences and Middle Devonian lacustrine strata. Key findings include the extent and inception of Lower Carboniferous delta systems and laterally equivalent basinal, mud-rich successions from the North Sea, across onshore UK to the Irish Sea, presented as a series of palaeogeographic time slices. Lying north of the Southern North Sea gas play, these successions contain coal, non-marine and marine mudstone source rocks with interbedded channel sandbody reservoir intervals in a stacked succession up to kilometres thick.

6pm, The Geological Society of London