How much oil seeps up naturally from the ocean floor?
Natural Petroleum Seeps Release Equivalent of 8-80 Exxon Valdez Oil Spills
http://www.whoi.edu/oilinocean/page.do?pid=51880&tid=282&cid=57286
natural petroleum seeps off Santa Barbara, California.
About a ahip tanker full per day from the various vents under the sea around the world. Plus a lot of heat and other hydrocarbons.