The Oil Drum

The calculation is incorrect. The world uses about 30 billion barrels a year. That is slightly more than 1 cubic mile per year. Not 16 cubic mile per day.

Assuming the total remaining recoverable oil in the world is 600 billion barrels, if you lay that oil evenly on the surface of the earth, it's a thin layer of slightly less than 0.5 milimeter thick. That tells you how precious petroleum is. If it were abiotic, vastly much more quantity of oil would have been found already.

If you divide that quantity by the total volume of the earth, it's only 8.8x10^-5 ppm of the earth's volume. That's how precious oil is and we should be grateful that the petroleum, which is of biological origin, is concentrated in a way for us to retrieve easily.

It's true abiotic methane is found in plenty else where in the solar system. Since earth is formed from the same primordal soup, one may reasonably suspect that the same abiotic methane may exist on earth. The very origin of life on earth requires a high concentration of organic material in the promordal soup that formed the earth.

But it's all irrevevant as pie in the sky, or as irrelevant as methane on the Titan, as long as we have not found where these methane are on the earth, or have no reasonable way of retrieving and utilizing these methanes. We already know there is plenty of methane hydrates, equivalent to several times the known petroleum reserves, right underneath the bottom of oceans. But we currently have no technology to fetch those methanes hydrates.