Geological evolution and hydrocarbon potential of the Hatton Basin (UK sector), north-east Atlantic Ocean

The deep-water Hatton Basin (flanked by the Hatton and Rockall Highs) is located 600km west of Scotland (NE Atlantic Ocean) on the western margin of the Eurasian continental plate. Prior to Atlantic opening the area was adjacent to SE Greenland. The basin straddles the UK/Irish median line. Water depths increase southwards from 1000m to over 1300m. The basin has never been licensed for hydrocarbon exploration and is currently the subject of ownership negotiations related to the UN Convention on Law of the Sea. Consequently it is under-explored. The deepest borehole penetration is by DSDP borehole 116 which reached TD at 854m below sea bed in the Late Eocene. The Pre-Cambrian metamorphic basement only crops out on Rockall Bank where high-grade gneiss and granulite have been sampled and dated at c. 1900 to 1700 Ma. This is a different terrane from that which underlies most of Scotland. Palaeozoic rocks have not been proved in the area but may provide some of the pre-rift basin infill. The Hatton Basin probably opened during the Cretaceous. Recent (2007) seismic data suggest the presence of tilted fault blocks on the basin margins. Mid Cretaceous (Albian) sandstones and mudstones have been proved at shallow depth on the Hatton High. The area was massively affected by Late Paleocene to earliest Eocene volcanism which emplaced several large central igneous complexes and caused widespread lavas which degrade the seismic data from the deeper geology. Atlantic rifting commenced west of the Hatton High at about 56 Ma. During the Cenozoic the basin was affected by differential subsidence and several unconformity-forming compressional events. Numerous potential hydrocarbon trap styles have been identified including syn-rift tilted fault blocks, folds, truncations, prograding fans, pinch-outs, scarp fans and traps related to sill intrusions. Reservoir intervals are likely to be present in the Cretaceous, Paleocene and Eocene. The overlying Oligocene to Recent sediments are mudstones and oozes and may provide a seal. The main risks for an accumulation are the presence of a source rock and the shallow occurrence of some of the potential traps.