Saglek Basin in the Labrador Sea, east coast Canada; stratigraphy, structure and petroleum systems

Abstract

Abstract Saglek Basin is the more northerly of the two major sedimentary basins along the Labrador margin of the Canadian east coast in which exploration drilling was undertaken in the 1970s-early 1980s. Saglek Basin has an area of over 100,000 km2, and contains a clastic-dominated succession of late Cretaceous to Pleistocene age. Nine wells were drilled in Saglek Basin, with only one significant discovery. The Hekja O-71 well, drilled in the northern half of the basin just east of Frobisher Bay, flowed natural gas with condensates and has reserves estimated at approximately 6.51 × 1011 m3 (2.3 Tcf). A new interpretation of seismic and marine Bouguer gravity data shows the very strong influence of reactivated basement structures on the overlying section. Earthquake activity along the Labrador Sea seismic zone is proposed as a possible cause for episodic venting of thermogenic natural gas through pre-existing fracture networks. This may account for the observations of persistent oil slick features on the sea surface observed in satellite radar data. The presence of these oil seep indicators in the southern part of the basin implies the existence of a second petroleum system that is more oil prone. Source rock analysis indicates that three formations in the post-rift succession of the basin have petroleum source potential. Previous studies have raised the issue of inadequate thermal maturation of these rocks in downgrading the petroleum potential of the basin. An integrated 4-D basin modelling study, that shows significant natural gas generation, estimated that volumes of 2.83 × 109 m3 (100 Tcf) could occur, along with a minor oil component, in self-sourced petroleum kitchens in some reservoirs and from sites deeper in the basin. Three separate prospect fairways are interpreted along the western side of the basin. Collectively, these observations suggest the petroleum potential of the Saglek Basin may be significantly higher than estimated previously.