Petroleum geology of the Irish Rockall Trough – a frontier challenge

Abstract

The Irish Rockall Trough is a frontier area recently opened for hydrocarbon exploration. The Trough, a NE–SW trending Mesozoic–Cenozoic basin, lies in water depths ranging between 500 m and 3000 m. Basin development began as early as the Late Carboniferous and a series of rift episodes continued sporadically throughout the Mesozoic and Tertiary. The most important of these occurred between the Late Jurassic and Early Cretaceous. The post-rift thermal sag phase followed in the Late Cretaceous and Tertiary. The resultant basin is characterized by thinned continental crust, a series of tilted fault blocks and a number of smaller ‘perched’ basins adjacent to the main basin-bounding faults. This paper presents an assessment of the petroleum prospectivity of the Rockall Trough by focusing on its stratigraphic and structural development, integrating the results from modelling work and providing concise play models. A suite of regional palaeogeographic maps are used to develop a full understanding of the stratigraphic history of the Trough. A structural modelling study is then discussed in which two regional seismic lines are interpreted and flexurally back-stripped. Finally, a source-rock modelling study is presented whereby the timing and extent of oil and gas explusion within the potential kitchen areas are examined. The conclusions of this work are illustrated on a series of play concept diagrams.