I've been noticing that oil seems to spread out if there is water close to the center of the field. Usually the single patches are rather close to each other, but in these cases they are all over the place.
I'm sure it's because it tries to spawn the oil patches, can't and then moves them to the edge of the water. Not a huge deal, just kind of unpretty.
Just as a note, it also happens when other resources take up the space. E.g. I had a coal field spawn inside an oil field and it made the oil spread out like that.
That will be more difficult to fix - simple way I did for water issues won't help.
It's a bit strange that one patch would be inside others outside - it should not be able to spawn oil over coal so it should be whole coal first or all oil wells first.
Only way to fix this would be to preplan all oil wells for patch and drop randomness completely. Then it could try to arrange them somehow. It would need to be pretty careful to make sure it doesn't break since there are many possible cases it can end up.
My guess is you would like to have them lined up for beacons - wouldn't that be to easy?