The earth sweats oil. Abiogenic (or abiotic) oil is not a “proven” theory, but neither is the theory that oil comes from dinosaurs (along with a lot of other “settled” science—which is not the same as “proven”).
I think it comes from dead plankton fallen to the bottom (black muck) and either lies dormant undiscovered, under former seabeds (Midwest, Mideast) or gravitates through underground passageways to coastal sites.
Otherwise, my bet is that it can be found in most places in the oceans and is being created daily by the sun, growing algae, deep ocean pressure and geothermal heat.
It is not a theory that oil is only found sourced to sedimentary basins, or that it contains microfossils from the organisms laid down in the layers where oil is found, or that it is so old we cannot measure its age with radiographic carbon dating.