Hi.
Normally crude oil seeps up through the sea floor, but in small quantities.
5.56mm
Yes:
naturally occurring oil seeps from the seafloor are the largest source of oil entering the world ocean? (https://oceanservice.noaa.gov/facts/oilseep.html)
[2000] Twice an Exxon Valdez spill worth of oil seeps into the Gulf of Mexico every year, according to a new study...Oil that finds its way to the surface from natural seeps gets broken down by bacteria and ends up as carbon dioxide, a greenhouse gas...."On water, oil has this wonderful property of spreading out really thin," said Mitchell. "A gallon of oil can spread over a square mile very quickly." So what ends up on the surface is an incredibly thin slick, impossible to see with the human eye and harmless to marine animals. (https://www.sciencedaily.com/releases/2000/01/000127082228.htm)
[2003] Recent global estimates of crude-oil seepage rates suggest that about 47% of crude oil currently entering the marine environment is from natural seeps, whereas 53% results from leaks and spills during the extraction, transportation, refining, storage, and utilization of petroleum. The amount of natural crude-oil seepage is currently estimated to be 600,000metric tons per year, with a range of uncertainty of 200,000 to 2,000,000metric tons per year. Thus, natural oil seeps may be the single most important source of oil that enters the ocean, exceeding each of the various sources of crude oil that enters the ocean through its exploitation by humankind. (Kvenvolden, Keith & Cooper, Cortis. (2003). Natural seepage of crude oil into the marine environment. Geo-Marine Letters. 23. 140-146. 10.1007/s00367-003-0135-0. https://www.researchgate.net/publication/225679680_Natural_seepage_of_crude_oil_into_the_marine_environment/citation/download)
[2009] "Natural Petroleum Seeps Release Equivalent Of Up To 80 Exxon Valdez Oil Spills." According to new research by scientists from UC Santa Barbara and the Woods Hole Oceanographic Institution (WHOI), that's how much oil has made its way into sediments offshore from petroleum seeps near Coal Oil Point in the Santa Barbara Channel... "One of the natural questions is: What happens to all of this oil?" Valentine said. "So much oil seeps up and floats on the sea surface. It's something we've long wondered. We know some of it will come ashore as tar balls, but it doesn't stick around. And then there are the massive slicks. You can see them, sometimes extending 20 miles from the seeps. But what is really the ultimate fate?"
Based on their previous research, Valentine and Reddy surmised that the oil was sinking "because this oil is heavy to begin with," Valentine said. "It's a good bet that it ends up in the sediments because it's not ending up on land. It's not dissolving in ocean water, so it's almost certain that it is ending up in the sediments." (https://www.sciencedaily.com/releases/2009/05/090513130944.htm)