History of the Arctic Ocean
During glaciations, the shelves down to ~100m depth would have been above sea level, but they would have been covered by ice sheets.

Geology.com
The actual "ocean floor" would still be deep water.
There is a general explanation of the oil formation here and here, although they don't say when (or where the continents were when the sediments were deposited), and again, this is on the shelves, not the floor.

"An overview of the petroleum geology of the Arctic" has:


  
  Maps of palaeogeography of the Arctic based on Golonka's maps for the Late Devonian, the Middle Triassic, the Late Jurassic and the Middle Palaeogene, representing the times of deposition of some of the major Arctic source rocks