Federalism may mean that states will fight for control of provinces that have oil. The fgs will need to make a strong national army, make revenue sharing laws, and resolve issues between states impartially to avoid disunity between states.
The huge oil reserves haven't been proven yet and it's size is begin estimated and tested currently. There were websites from 2015 that stated it's oil reserves (110 billion barrels) with no reference
Not sure about Libya but Somalia has definitely more oil than Nigeria and Kuwait combined. I predict somalia deposits lie in between 110 to 400 billion barrels of oil. Somalia could potentially be the largest oil producer in the world.