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I did a google image search for a world map of offshore oil. Surprisingly I found virtually nothing. I had to search country by country for such maps.

I noticed most if not all were located very near the country's shore, on the continental shelf. These are fairly shallow seafloors, not even going below 1 km deep.

I guess this is because, it's easiest to explore (and drill) in the shallow regions first. But what I want to know, is there good reason to believe the very deep ocean also has oilfields.

So here is my question: Given our current understanding of geological history, is it likely that the oceans have decent oilfields located underneath the very deep seafloor?

"Decent oilfield" would be something like 10+ million barrels of oil without more sulfur than a Heavy Grade of Crude.

We have good bathymetric data of most oceanfloor, e.g., the underwater mountain-range in the mid-Atlantic, and the superdeep trenches following the Mariana Islands. I'm hoping that just by looking at the shape, we can make a good prediction where oil is located.

My only hint is a few very deep regions in the Gulf of Mexico, like this field that's 2.7 km below the sea. I am not aware of any other deep offshore platforms. I noticed the Gulf of Mexico has a fairly...what's the word here...bubbly shape in the deep parts.

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    $\begingroup$ I'd say that it's unlikely that ocean floors would have oil. They're geologically young, being created by lava from mid-ocean ridges. See e.g. ngdc.noaa.gov/mgg/ocean_age/data/2008/ngdc-generated_images/… Most of the Gulf of Mexico doesn't seem to be ocean floor at all: perhaps someone more knowledgeable can explain why? $\endgroup$ – jamesqf Aug 26 '17 at 6:20
  • $\begingroup$ Our bathymetric data for most of the deep ocean is surprisingly low resolution, as we discovered whilst searching for flight MH370. There are parts of the Moon where the topography is more well known than the bottom of the ocean. $\endgroup$ – bon Aug 27 '17 at 18:21
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Are there probably decent oil fields located in the middle of the ocean?

tl;dr: no.

Hydrocarbon deposits form by thermal maturation (i.e. slow and mild heating) of buried organic matter (i.e. dead things) in sedimentary rocks. This is exactly why you find hydrocarbons...

very near the country's shore, on the continental shelf

...because that's exactly where you find sedimentary rocks.

In contrast, the deep ocean basins are igneous rocks (mostly basalts) overlain by thin marine sediments with very little organic material. Whatever organic material is there, it never has the chance for maturation. It's either very cold, or gets heated in subduction and is lost forever in the deep mantle.

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  • $\begingroup$ However , there are large deposits of hydrate - methane /water ice. $\endgroup$ – blacksmith37 Aug 26 '17 at 15:40
  • $\begingroup$ By any chance, is the Gulf of Mexico (and perhaps the Caribbean Sea too) entirely made of sedimentary rock? $\endgroup$ – DrZ214 Aug 26 '17 at 19:27
  • $\begingroup$ @DrZ214 the geology of that area (especially the Caribbean) is very complex. I suggest you ask another question regarding that. $\endgroup$ – Gimelist Aug 27 '17 at 0:32
  • $\begingroup$ Just asked it here: earthscience.stackexchange.com/questions/12157/… $\endgroup$ – DrZ214 Aug 27 '17 at 3:32
  • $\begingroup$ You could mention Seafloor spreading , the reason for igneous rocks. $\endgroup$ – Keith McClary Sep 3 '17 at 0:29

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