This pretty much sums up why Nigerian economy is under so much pressure from the falling oil prices:

"Saudi Arabia, Kuwait, Qatar and the United Arab Emirates have combined savings of $2.5 trillion dollars. Unlike Iran, Nigeria and Venezuela, they can afford to be less concerned about falling prices because they have built up a deep financial cushion."

What happened to all the excess crude oil earnings?

Anyway given Saudi Arabia wants oil prices to fall to fight shale gas, Nigeria is going to face more pressure in the coming months and years