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The Peace River oil sands of northwestern Alberta contain an estimated 92 billion bbl of bitumen trapped in an updip pinch-out of the Lower Cretaceous Bluesky and Gething Formations. The geologic reservoir characteristics of the Peace River oil sands are being mapped on a regional scale through the use of core and geophysical logs. Four wells per township are used wherever possible. A computerized data file on each well consists of basic well data, tops of the Bluesky and Gething Formations, and oil sand reservoir and the underlying pre-Cretaceous unconformity, and a coded lithology log. The lithology log is kept simple due to the limits of geophysical log interpretation but attempts to quantify sand, shale, interbedded sand and shale, oil, and water. Logs have been calib ated wherever possible with core control. Because the data are stored as a log of the well, a wide variety of useful maps can be generated by the computer. These include maps showing structure, sand/shale ratios, gross and net pay thicknesses, basal water, top water, lean zones, and uninterrupted pay.
Recognition of four major facies including continental, tidal flat, shoreline and shallow marine, and tidal channel deposits has led to the proposal of an estuarine model for sedimentation within the Gething Formation. Isopach maps from the top of the Bluesky and Gething Formations down to the pre-Cretaceous unconformity show a regional southeast to northwest drainage trend on the unconformity surface. Similar trends are seen in the main sand bodies. Coordination of computer-generated maps with the facies model highlights areas which satisfy specific criteria that may be critical in determining the applicability of a particular in-situ recovery method.
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