This section surveys the opinion of technical authorities within the industry on the present United States reserveresource position in petroleum. At the start it is necessary to relate the industry terminology in which existing estimates are presented to the terminology outlined in the Introduction.
The term "reserves" as used in the petroleum industry is normally a contraction of the term "proved recoverable reserves." The American Petroleum Institute provides an authoritative and explicit definition as follows:
Proved reserves are both drilled and undrilled. The proved drilled reserves, in any pool, include oil estimated to be recoverable by the production systems now in operation, whether with or without fluid injection, and from the area actually drilled up on the spacing pattern in effect in that pool. The proved undrilled reserves, in any pool, include reserves under undrilled spacing units which are so close, and so related, to the drilled units that there is every reasonable probability that they will produce when drilled.1
Although additions to proved reserves can accrue through improved recovery techniques, through more favorable eco-____________________