I've always thought that's a heck of a lot of petroleum to be formed from plants.
Coal perhaps, but not gazzillions of barrels of oil.
Jupiter’s atmosphere is composed of about 90% hydrogen and 10 % helium. There are only minute traces (0.07%) of methane (CH3), water, ammonia, and rock dust.
Since methane was one of those “biotic” materials under discussion, either there is life on Jupiter or methane is abiotic.
The processes for abiotic natural gas appear a lot more likely than for abiotic oil.
Finally, it does not make much difference how it is made. In addition to oil you still need a large enough trap [cap rock to keep it from rising — and something to keep it from migrating further horizontally] and suitable reservoir rock [porous and permiable] at a depth no so deep as to cook down the oil to have an economically viable deposit.