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Sediments of Kimmeridgian to Late Ryazanian age form a group of key hydrocarbon play fairways in the syn-rift Jurassic of the North Sea. The perceived yet-to-find reserves of these often subtle plays, lying at or below seismic resolution, have attracted considerable industry attention over the past few years. Reserves are currently estimated by BP Exploration at 1 to 5 billion barrels of oil equivalent, reservoired in three play systems: (1) apron fans (e.g. Brae type); (2) basin floor fans (e.g. Miller, Galley, Ettrick and Magnus types); (3) shallow marine shelf (e.g. Ula, Gyda, Fulmar, Piper, Clyde types).In order to assess the future exploration potential of this play fairway, a high resolution, predictive, sequence stratigraphy was erected for the North Sea Late Jurassic. The stratigraphic framework combines data from over 500 exploration wells with seismic and field data (Magnus, Brae, Miller, Ula, Gyda and Clyde).In the Late Oxfordian to Late Ryazanian, a total of 11 genetic stratigraphic sequences have been defined. They are bounded by maximum flooding surfaces which, within the limits of the biostratigraphy, represent basin-wide isochronous events across NW Europe and can be recognized in exploration wells and at outcrop from Greenland to the Wessex Basin. The maximum flooding surfaces have been biostratigraphically calibrated to provide a consistent and easily identifiable stratigraphic framework. Candidate sequence boundaries have been interpreted within this stratigraphic framework, from basin-ward shifts of facies belts, using sedimentological and wireline log data. The combination of these stratigraphic methods has produced a very powerful tool to predict the presence and distribution of potential reservoirs and play types across the entire North Sea Basin from outcrop in East Greenland to the offshore Netherlands.The model suggests that three major cycles of sand input into the basin can be recognized with an overall marked decrease in net sand content with time. Each cycle is bounded by tectonically enhanced maximum flooding surfaces representing major periods of basin floor reorganization. The intervening maximum flooding surfaces temporarily switch off sediment supply to the basin but do not offset depocentres. These events can form important, field-wide permeability barriers.It is proposed that the tectonically enhanced maximum flooding surfaces are a response to tectonic subsidence during maximum relative sea-level rise, whereas maximum clastic progradation occurs from basin margin uplift during relative sea-level fall. The model is considered to have application at regional and field-specific scales; for example, prediction of both basin floor fan distribution and potential intra-reservoir permeability barriers.

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An integrated approach using plate tectonic analyses and detailed comparative stratigraphy of the North Atlantic has placed new constraints on the Mesozoic to Cenozoic geological history of the Atlantic margin of NW Europe. Key reconstructions from Mesozoic time to the present day have been plotted to show the evolution of the North Atlantic, and in particular the Rockall Trough. The reconstructions show Rockall Plateau attached to Greenland from Late Paleozoic time (380 Ma) to Late Cretaceous time (83 Ma) since when Rockall remained attached to Eurasia. The Rockall Trough probably initiated during end-Carboniferous to Early Permian time and underwent further stretching episodes in the Early Triassic, Early Jurassic, Middle Jurassic, Late Jurassic, Early Cretaceous, mid-Cretaceous and Late Cretaceous to give the present-day Rockall Trough configuration. The Permo-Triassic rift was dominated by oblique opening with a left-lateral component of strike-slip. Jurassic through Early Cretaceous extension was characterized by predominantly left-lateral strike-slip with a minor dip-slip component in the Faeroe basin and north Rockall Trough, and mainly dip-slip extension in central and south Rockall Trough. In Early Cretaceous time (mid-Aptian) the majority of the United Kingdom Continental Shelf (UKCS) Atlantic margin underwent orthogonal opening followed by continued extension in Late Cretaceous to Paleocene time, culminating in the opening of the North Atlantic west Rockall Plateau. The main Late Jurassic and Early Cretaceous rift episodes conveniently divide the stratigraphy into pre-, syn- and post-rift megasequences which form gross play fairways along the North Atlantic margin. Analysis of these fairways permits integration of data from both mature (e.g. North Sea) and immature (e.g. North Atlantic margin) exploration provinces and helps provide a consistent, predictive approach to the assessment of future hydrocarbon potential of the frontier basins lying along the North Atlantic margin.

Abstrart: Late Westphalian inversion structures on the Variscan foreland display wide variations in orientation that are the product of the underlying basement grain. The orientation of the major basement lineaments in relation to the direction of maximum shortening also determined the severity of deformation of the inverted basins. NE-SW-trending faults were oriented roughly perpendicular to the NW-SE to NNW-SSE direction of maximum shortening determined from thrust transport directions in the Variscan orogen to the south. As a consequence, NE-SW-trending basins in the Variscan foreland have been strongly inverted, the Silesian post-rift fill has commonly been expelled from the basins and the syn-rift sediments have been deformed by chevron folds (Dublin and Bowland Basins). In contrast, the N-S-and NW-SE-trending faults were oriented more obliquely to the direction of maximum shortening and, as a consequence, display a significant component of oblique slip. This oblique slip component is manifested as en-echelon periclines and flower structures. In general, the N-S-and NW-SE-trending basins were less strongly inverted and the Silesian post-rift fill has been retained.

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