POLAN, KEVIN P., KEVIN S. SLAUENWHITE, and DAVE J. HEMPHILL
The estimated gas in place volume of 56,000 million cubic meters (2 tcf) of liquid rich, very sour gas makes the Caroline discovery the most significant find in the Western Canadian sedimentary basin in the past 20 years.
The Beaverhill Lake group is very important to the petroleum industry of western Canada. Major oil fields of north-central Alberta such as Swan Hills and Virginia Hills were discovered in the 1950s. The deep sour gas potential of the play was demonstrated in the 1970s by discoveries in the Erith-Brown Creek area. In 1986, the Caroline pool became the most recent discovery along this trend; it consists of a dolomite fringe of exceptional reservoir quality along
the seaward edge of a limestone platform of Devonian Frasnian age (Swan Hills Formation).
An interesting aspect of Caroline is the presence of three gas-water contacts in this stratigraphically trapped pool, which is devoid of structural complications. The deepest contact, at 2726 m subsea, is compatible with regional water and local gas pressure-depth response. The second and third contacts, at 2655 m and 2603 m subsea, are anomalously shallow. An obvious possibility is that there are in fact three pools. However, pressure, gas composition, and seismic and structural data show that the two shallower contacts are due to perched water trapped behind spillpoints formed by downdip reentrants.
AAPG Search and Discovery Article #91012©1992 AAPG Annual Meeting, Calgary, Alberta, Canada, June 22-25, 1992 (2009)