How much of the petroleum ever formed has made it into reservoir rocks?
In its 1995 assessment of total world oil supplies, the U.S. Geological Survey (USGS) estimated that about 3 trillion barrels of recoverable oil originally existed on Earth and that about 710 billion barrels of that amount had been consumed by 1995.
Britannica

There may be much larger quantities that are not &quot;recoverable&quot;, depending on technology and economics.
Also, for example, 914 persistent natural seeps across the Gulf of Mexico collectively discharged about 500,000 barrels of oil per year. If that has been seeping for millions of years, that is a lot of oil that is not in reservoirs.