The recoverable volumes of oil contained in deposits of extra-heavy oil and natural bitumen are immense. If oil in place for conventional oil is estimated to be about three times original reserves, then remaining oil in place, after deduction of cumulative production, is about 4 925 billion barrels. On the same basis, the remaining oil in place in VENEZUELA S Orinoco Oil Beit is about 1 968 billion barrels, plus 235 billion barrels of contingent resources, and, in northern Alberta, Canada, an additional 1455 billion barrels of bitumen in place in the less well known carbonate deposit. Future deposit on the scale of the Orinoco Oil Belt are not expected but additional exploitable natural bitumen deposits are known in the Russian federation, the United States, and elsewhere.

Relatively small portions of the two major deposits are currently being produced, with this production increasing annually, New technologies have allowed production rates comparable to those of conventional oil reservoirs. Major cost-reduction breakthroughs in upgrading, transportation, and relining are enhancing the movement of these hydrocarbons into mainstream world oil supply.