Reserve Growth in Oil Pools and Fields of Alberta, Canada
Reserve growth is recognized as a major component of additions to reserves in most oil provinces around the world. Such additions come from two sources: (1)discovery of new fields, and (2) reserve growth within the existing fields. The latter results from new pool discoveries and extensions within fields, improved knowledge of reservoirs over time leading to change in estimates of original oil-in-place, and improvement in recovery factor through application of enhanced oil recovery methods, horizontal/multilateral drilling, and 4D seismic.
Objectives of the reserve growth study for oil pools of Alberta, Canada were to (1)evaluate historical oil reserve data in order to assess the potential of reserve growth; (2)develop reserve growth models/functions to help forecast hydrocarbon volumes; (3) study reserve growth sensitivity to various parameters - for example, pool size, porosity, and oil gravity; and
4 compare reserve growth in oil pools and fields of Alberta with those from other large petroleum provinces around the world.
The reported known recoverable oil in Alberta increased from 4.5 billion barrels of oil (BBO) in 1960 to 17 BBO in 2005. However, because some of the pools were dropped for lack of adequate data, the known recoverable oil in this study changed from 4.2 to 13.9 BBO - an increase of 9.7 BBO. New discoveries contributed 3.7 BBO and reserve growth added 6 BBO. Reserve growth was determined to be mostly in pools with more than 125,000 barrels of known recoverable oil. Pools with light oil accounted for most of the total known oil volume and therefore mirrored the overall pool growth. However, although pools with heavy oil (gravity less than 20 API) make up only a small share (3.8 percent) of the total recoverable oil, they showed significantly larger cumulative growth compared to pools with medium and light oils. Pools with high porosity reservoirs (greater than 30 percent) grew more than pools with lower porosity reservoirs. Reserve growth models show almost twice as much growth at field level than at pool level, possibly because of there being more than one pool in a field and their different discovery years.
Over a 25-year period, the cumulative reserve growth in Alberta oil pools is less than in other important petroleum-producing areas such as Saskatchewan Province, West Siberian Basin, Volga-Ural Basin, U.S. onshore fields, and U.S. Gulf of Mexico, although growth at the field level compares well with that in U.S. oil fields.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009