The Upper Devonian Grosmont Formation is a bitumensaturated, carbonate unit located in northern Alberta. It is considered to be one of the worl's next largest unconventional oil resource plays. Since early 2006, there has been an increased interest in Grosmont resources exhibited by a range of companies including super-majors.
Several in-situ pilot tests were conducted in the central portion of this area in the 1970s and 1980s utilizing steam and in-situ combustion processes. Similar to field tests in the McMurray Formation oil sands prior to invention of the steam assisted gravity drainage (SAGD) process, none of the early recovery technologies tested were proven to be economic. As the "gravity" drainage process has been proven successful in commercial development of the McMurray Formation oil sands since mid to late 1990s, the recovery potential for the Grosmont Formation should be re-evaluated based on improved recovery techniques.
Results from cyclic steam stimulation (CSS) field tests are compared and analyzed to understand the similarity and fundamental differences in reservoir properties between the McMurray Formation oil sands and the Grosmont Formation carbonate rocks. A preliminary interpretation is provided for laboratory test results for solvent processes applied to Grosmont carbonate cores. The scaling considerations from the laboratory results to field expectations are discussed. The paper also provides a direction for future studies and optimization opportunities for reservoir recovery leading to the commercial development of Grosmont carbonate reservoirs.
The estimated original bitumen in place (OBIP) in the Grosmont carbonate reservoir is 51 billion m3 or 320 billion bbl [1]. It is by far the largest heavy oil carbonate reservoir in the world. In comparison with the McMurray Formation in the Athabasca oil sands area, the carbonates of the Grosmont Formation have a very complex porosity and fluid mobility system as well as a highly heterogeneous oil saturation, a more hydrophobic rock matrix, and a poorly understood geomechanical property. The platform carbonates of the Grosmont Formation that form the best potential reservoirs have predictable and mappable lithology over several hundred square kilometers whereas the vertically homogeneous channel sandemulsification of heavy oil in formation brine under slight interfacial disturbance. Tertiary oil recovery in sandpack flood tests reached more than 20% OOIP. Liu et al.[7] studied the synergy of alkali and surfactant in emulsifying a heavy oil in brine. deposits that comprise the best-performing McMurray Formation reservoirs are limited in areal extent and require significant delineation in order to map accurately. While the Grosmont reservoir is very attractive from the resource point of view, the differences in reservoir characteristics pose significant challenges to reservoir development.
The first field operation attempt in the Grosmont Formation started in December 1974 by Union Oil in the Chipewyan River area, Section 21 of T89-R21-W4. The objective of the pilot was to test reservoir injectivity, well completion techniques and to recover bitumen samples for characterization. One cycle of CSS steam injection and production was conducted in two vertical wells, 14B-21 and 11E-21. The operation ended in April 1975.
