Title: Prediction of deep-water stratigraphic traps developed across the syn-rift to post-rift transition in Atlantic-margin basins
Researchers: Lewis Whiting and Prof. Peter Haughton
The Porcupine Basin, located on the Irish Atlantic Margin, is recognised as a prospective basin for potential deep-water petroleum plays. It displays a strong north-to-south lateral strain gradient along with evidence for hyperextension. Mid-Late Jurassic rifting was followed by a protracted phase of thermal subsidence during the Cretaceous. However, a feature of the post-rift Cretaceous stratigraphy is the presence of prominent unconformities that cap deeply eroded and structurally-rotated lowermost Cretaceous successions. Curiously, the latter are mainly preserved perched on the main basin flanks and are passively overstepped by the younger Lower Cretaceous infill. In the main basin, the Lower Cretaceous is comprised of laterally variable clastic packages and important localised erosional surfaces. Identifying the relationship between the stratigraphy of the basin margins and basin centre is critical for understanding the evolution from normal to hyperextension to major thermally-controlled subsidence focussed along the basin axis.
The present study uses a combination of 2D and 3D seismic data and well information to identify, correlate and examine the character and distribution of the Upper Jurassic and Cretaceous successions. Seismic and depositional mapping, combined with decompaction of the Lower Cretaceous succession across the basin, provides an enhanced understanding of the syn-rift to post-rift sedimentary evolution and tests the hypothesis that fault-controlled extension led directly to underfilled deep bathymetry. The results provide important clues to the timing, distribution and potential reservoir quality of deep-water sedimentary systems in hyperextended basins.