Petroleum in these rocks likely was generated beneath Western Alaska North Slope and migrated northeastward into NPR-A.

The Nanushuk Formation together with the Torok Formation below it forms a huge wedge of sediment deposited in a deep water basin and stretches from north of the Brooks Range beneath the Alaska North Slope to the adjacent offshore.

It was deposited in shallow water and includes potential reservoirs in deltaic, shoreface, and fluvial sandstones.

The USGS found large-scale folds and faults in the South of the formation and evidence, that the rocks have been heated to temperatures at which oil is converted to natural gas.

[1] These discoveries were possible, because of technological advancements like three-dimensional seismic data processing, extended reach drilling.

[3] In 2013, Repsol and Armstrong Energy discovered the Pikka oil field by drilling a discovery well they called Qugruk 3.

[5] Per USGS in 2017, industry estimated this Pikka-Horseshoe pool may hold more than 1.0 billion barrels (160 million cubic meters).

[4] In May 2024 Repsol and Santos Limited subsidiary Oil Search were looking to sell 20-25% of their non-operating interest in the Pikka unit.