The new update includes one startup option to enable deep sea oil generation and oil rigs to extract it. A second startup option can be selected to delete all the oil on land, so you must go to sea to get it. Oil at sea is now generated using the vanilla oil spawner, so it will be just as frequent in the ocean as if the whole map were land with normal oil on it.
Note that SeaBlock intentionally disables deep sea oil generation, so I incorporated that into this update as well. I'm not sure if it needs to be an option to override it and make oil anyways.