Mr. Husseini makes the claim in an article in Petroleum Intelligence Weekly, disagreeing with that publication's numbers and "common methods" of reserve estimation. He says the estimates include "unconventional hydrocarbons, inaccessible oil accumulations and unconfirmed recoveries, none of which fit the current definitions of proven or probable reserves." An example he sites, according to our source article from NewsMax, is the 140 billion barrels of Canadian bitumen estimate that is often reported as "proven" reserves. He believes only a small fraction of that amount could be turned into a useful fuel.
Perhaps the oil-supply future will become more clear with the completion of a study this November by the International Energy Agency. They are considered a reliable source of oil information and are currently analyzing depletion rates and are talking with usually-secretive governments. We suspect that many "experts" will continue to weigh in on the topic long before the study's release.