This chapter summarizes the methodology followed in creating the oil and gas field outlines shown in each relevant Atlas chapter. Also included is a summary of oil and gas reserves and production distribution, again in accordance with Atlas stratigraphic intervals.
The original assignment for this project was to provide up-to-date and reliable oil and gas field outlines, reserves and production summaries for the 13 producing stratigraphic intervals embraced by this Atlas. This target was achieved using Digitech's Production Data System and the Geological Survey of Canada's PETRIMES reserves database.
The producing oil and gas wells were identified and located using PDS (Production Data System), marketed by Digitech Information Services Limited of Calgary. Retrieval of these data for producing wells was obtained using Alberta data that had been updated to January 31, 1991, British Columbia data updated to October 31, 1990, and Saskatchewan data updated to August 31, 1990. Further clarification of producing zone and production figures for specific horizons in each province was obtained from provincial reports listed in the references at the end of this chapter.
Reserves, cumulative production and size distribution data were provided by P. J. Lee of the Institute of Sedimentary and Petroleum Geology in Calgary, using the PETRIMES reserves database (Lee and Tzeng, 1988), updated to 1991.
The first step in identification of producing wells was to request a printout from Digitech listing all producing oil or gas wells for each of 17 major stratigraphic zones. The wells were listed in order of location (i.e., U.W.I.) and current status; field, zone and pool were given. The 17 major stratigraphic zones included several, such as Elkton, Shunda and Banff, that were later lumped together to provide the production data for the 13 producing zones discussed in this Atlas. Included in the retrieval were all abandoned and suspended oil and gas wells, which were identified as such under the current status column. Digitech also provided maps, at a scale of 1: 500 000, showing the location of all producing oil or gas wells for each horizon.
The second step was to outline and name all the pools and fields on these maps, using the printouts as a reference. All wells in the same pool were outlined in red by tracing a smooth line around the perimeter wells at a distance of approximately one legal subdivision. This has been described as the "rubber band" method, although indentations were carefully included. All of the pool outlines belonging to the same field were then outlined in blue, following the same "rubber band" method.
In addition to outlining all field boundaries and assigning the proper field names, major fields were identified by a special symbol, so that only the names of these major fields would be printed on the final maps provided for the Atlas. There are many small oil or gas fields that need not be identified by name on the Atlas maps, and this method thus allowed deletion of the names of these smaller fields. Major fields were arbitrarily selected on the basis of large size and number of wells, as likely being among the top 20 fields for that particular horizon. Careful review of reserves data commonly resulted in change of apparently minor fields to the major field designation.
The third step was to return these maps with red pool outlines and blue field outlines to Digitech for digitization, so that these outlines could be retrieved on any scale. Thorough verification of these digitized oil and gas pool and field outlines was carried out before the final 1: 2 500 000 scale maps for each of the Atlas' major 13 stratigraphic intervals were ordered.
The fourth step was to request these digitized pool and field outlines from Digitech, in maps at a scale of 1: 2 500 000, showing all field outlines for each stratigraphic interval, but names of only the major fields. The individual producing wells and pool outlines were deleted to reduce overprinting. This step completed the retrieval of producing well locations and digitized pool and field outlines and names from Digitech.
The fifth step was the retrieval of reserves and production data for every oil and gas field within each of the 17 stratigraphic horizons. These data were obtained from the Institute of Sedimentary and Petroleum Geology, using the PETRIMES package. Retrievals were made of all producing pools and of all producing fields within each interval. Close correlation was found between the wells, pools and fields on Digitech's PDS system and on PETRIMES.
The sixth step involved compilation from PETRIMES of the reserves and production statistics for the top ten fields in each interval. Some zones, such as the Permian and Dunvegan, showed small individual field reserves, so that a lower limit of 1000 x 106m3 (i.e., 35 BCF) initial established marketable gas reserves or 1 x 106m3 (i.e., 6 MMBbls) initial established recoverable oil reserves was set. The size distribution of individual pools within each horizon was also retrieved through PETRIMES and is included in the statistical summaries.
Minor problems were encountered in assigning production from some stratigraphic intervals because of the broad stratigraphic range of the producing formation. For example, production from the Mississippian Rundle Group is assigned to the Debolt-Elkton interval, even though the Rundle extends down into the Shunda-Pekisko interval. This arbitrary designation of Rundle to the Debolt-Elkton has proven satisfactory; however, the occurrence of a few Rundle fields beyond the Debolt-Elkton wedge edge indicates that in these cases Rundle production is derived from the Shunda-Pekisko.
The Nikanassin is generally regarded as Late Jurassic to earliest Cretaceous in age, and another arbitrary decision was made to assign all Nikanassin production to the Jurassic stratigraphic interval.
Similarly, the Granite Wash is arbitrarily assigned to the Elk Point, and not extended down into the Cambrian. The Wapella is assigned to the Lower Mannville rather than the Jurassic, Cantuar to Lower rather than Upper Mannville and Unity to Lower Mannville rather than Viking.
Production from the Camrose member in the Wainwright field is assigned to the Woodbend rather than the Winterburn.
In southern Alberta, five major oil fields are listed as producing from the Blairmore, without clarification as to Upper or Lower Blairmore (i.e., Mannville). In such cases, computer retrievals assigned such production to the uppermost zone. However, these five fields, namely Bellshill Lake, Bantry, Cessford, Taber and Taber South, produce primarily from the Lower Mannville.
In a few major gas fields, production is primarily derived from solution gas associated with major oil production. For example, Beaverhill Lake gas production from the Swan Hills and Judy Creek fields is reflected in only two gas wells, even though these two fields are among the largest Beaverhill Lake gas fields. Because oil and gas fields are shown together for each interval, this anomaly is not apparent on the maps.
Last modified: August 20, 2008
