ABSTRACT

This paper presents a two-part analysis of conventional crude-oil discovery rate in Alberta. Both recoverable oil and oil-in-place are considered. The first part of the analysis is simple and deals with discovery in the province as a whole. The second is an extension of the simple analysis and examines the growth of reserves in seven major plays in the province; the D-3, D-2, Swan Hills, Pembina-Cardium, Gilwood, Rainbow-Zama and Viking. All other reserves were grouped and regarded as another major play category. Current estimates of reserves were used and no further appreciation of these reserves was considered. This omission is not serious so far as the principle of discoveries is concerned.

The analysis is based on the postulate: The rate of crude oil discovery is proportional to the accumulated geological knowledge and the amount of undiscovered oil.

In order to test the validity of this statement, it was cast into mathematical form. The resulting equations were compared with the data for each major play and the cumulative provincial reserves data. Agreement between theory and data was good and would tend to confirm the postulate.

The theory is useful for explaining the seemingly erratic growth of provincial reserves. In reality, additions to the total provincial reserve are simply the sum of the additions occurring in each major play. In contrast to the aggregate provincial reserve, discovery of reserves within a play follows an orderly pattern. Once the play has been discovered, the largest fields are found quickly. As exploration continues, all major pools are located. Any further drilling results in the discovery of small pools that contribute relatively insignificant amounts to either the play or the provincial reserve. All Alberta plays exhibit this pattern. The apparent randomness in the growth of provincial reserves results from the sporadic discovery of new plays coupled with the simultaneous activity in other plays in various stages of maturity. With most plays in the middle to late phase of development, any future major additions to the provincial reserve must come from some new horizon or environment not currently thought to be productive.

The analysis is not intended to be used as a prediction at this time. However, it is obvious that unless several major new plays are discovered, the province's ultimate reserve could be considerably below the current estimate of 20 to 25 billion barrels espoused by the Energy Resources Conservation Board and the Canadian Petroleum Association.