Canadian Society of Geologists - University Outreach Lecture Tour

The : a massive "by-passed" pay zone.

Jen Russel-Houston, Ph.D., P. Geol., Osum Corp., , [email protected]

The Upper Grosmont Formation located in is a bitumen-bearing carbonate unit with an estimated 50.5 billion cubic meters (318 billion bbls) of bitumen in place (ERCB, 2008). Recovering just 20% of the resources within the Grosmont would increase 's reserves by about one-third. Currently, no recovery has been assigned to the Grosmont Formation by any corporate or government agency.

The Grosmont Formation carbonate rocks are richly saturated with bitumen in the Saleski area of northern Alberta. The shallow marine carbonate strata dip to the southwest and are eroded at the angular with the overlying -aged clastic rocks. The Grosmont Formation has A. Stratigraphy of the Saleski Area highlighting the angular unconformity of the Devoian been divided into four informal members; the Grosmont A, B, C, Grosmont with the Cretaceous . Vertical exaggeration is 50 x. B. Map of and D in order of decreasing stratigraphic age. The lithofacies Alberta with the Saleski area identified and shown at a smaller scale. Subcrop edges are marked of the Grosmont Formation at Saleski represent open marine to that represent where the Grosmont strata are eroded to zero thickness at the sub-Cretaceous restricted marine deposits and record an overall shallowing- unconformity. upward succession. The sediments were deposited in a wide carbonate platform setting (150 km by 600 km) and subjected to regional diagenetic processes related to the unconformity. The lithofacies are correlatable over hundreds of square kilometers. The Grosmont C and D units experienced early matrix dolomitization by seepage reflux and as a result were more susceptible to late-stage solution enhancement by meteoric waters when the carbonate units were uplifted and exposed during the Late to Early Cretaceous. This diagenetic history resulted in the Grosmont C and D units having a complicated porosity network of matrix porosity, vuggy porosity, solution-enhanced fractures, and breccias related to karstification.

The Grosmont Formation was first drilled in 1949 (Imperial Grosmont No. 1, 100/13-17-67-23W4) and described formally by Belyea in 1952. This massive resource was not developed because the bitumen was too dense (7o API) and too viscous (over 1 million cp) to flow to surface. The Grosmont was "by-passed" and the deeper, less viscous and less dense oils were preferentially produced. In the 1970s and the 1980s steam was injected into vertical wells to reduce the viscosity and mobilize the bitumen within the Grosmont in a process called cyclic steam stimulation (CSS). Steam drive and in-situ combustion where also tested. The early field tests produced significant amounts of bitumen (Harrison, 1982). The Grosmont pilots also had some operational issues that were the result of inexperience or mechanical errors, unrelated to reservoir performance (Jiang et al, 2009).

During the same time period, pilots using steam to produce the bitumen from the clastic McMurray Formation were also yielding encouraging results. The McMurray Formation in the Athabasca Core from well 100/07-08-085-18W4, 342 to 347 meters depth; cleaned (buff) region and the in the Cold Lake region and bitumen saturated (black) core were closer to infrastructure and as a result were selected as the samples from the Grosmont C, vuggy locations of the first commercial in situ steam developments. dolomudstone facies. Note vugs and The relative inaccessibility of the Grosmont Formation and the solution enhanced fractures. operational issues encountered in the early pilots guided industry away from commercial development of the Grosmont Formation. Technological inventions including 3D seismic, SAGD (steam assisted gravity drainage), VAPEX (solvent vapor extraction), hybrid solvent steam processes, improvements in the CSS method, horizontal drilling, and advancements in completion technology have all been applied to the Cretaceous-aged clastic reservoirs. Given the recent technological advancements that have occurred in bitumen recovery, it is Dolomudstone, Grosmont D, 00/07-08-085- time to return to the massive "by-passed" pay zone that the Grosmont Formation represents. 18W4, 318.60 m. Plain-polarized light. In the highly porous part of this field of view In 2007-09, Ltd. in partnership with Osum Oil Sands Corp. conducted a cold solvent (identified by blue epoxy), dolomite rhombs have been affected by intense leaching injection/production test in a single vertical well in section 26 of T85-R19-W4. The test demonstrated resulting in extremely high inter- and the feasibility of the cold solvent process and marked the return to the development of the Grosmont intracrystalline porosity. Diagenetic alteration Formation. Osum and Laricina will commence a horizontal well SAGD and solvent pilot in the has obliterated original depositional fabric. Grosmont in late 2010. Successful results from the pilot will bring the Grosmont bitumen, once by- passed, closer to commercial development.

Belyea, H.R. 1952. Notes on the Devonian System of the north -central plains of Alberta: Geol. Surv. Canada Paper 52-27. ERCB (Energy Resources Conservation Board), 2008. Alberta's Energy Reserves 2007 and Supply Demand Outlook 2008-2017. Statistical Series, ST98-2008, pp. 226. Harrison, R. S. 1982. Geology and Procduction History of the Grosmont arbonate Pilot Project, AB, Second UNITAR Conference on Future of Heavy Crude and Tar Sands, Caracas, Venezuela, February 7-17, p 199-204. Jiang, Q., Yuan, J., Russel-Houston, J. Thornton, B. and Squires, A. 2009. Evaluation of Recovery Technologies for the Grosmont Carbonate Reservoirs. Canadian International Petroleum Confernece, Society of Petroleum Engineers, SPE 2009-067, pp.11.

Jen Russel-Houston is the Geoscience Manager with OSUM Oil Sands Corp. in Calgary. BIO

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Queen’s University – Monday March 15, 2010 12:00 – 1:00 PM Room TBA

University of Toronto – Tuesday March 16, 2010 12:00 – 1:30 PM Room TBA

University of Waterloo – Wednesday March 17, 2010 12:00 AM to 1:30 PM Room TBA

Dalhousie University – Thursday March 18, 2010 12:00 AM to 1:30 PM Room TBA

Memorial University – Friday March 19, 2010 12:00 AM to 1:30 PM Room TBA

Lunch or snacks and drinks will be served

______For more information on the Canadian Society of Petroleum geologists visit: www.cspg.org For more information on the University Outreach Program’s lecture tours visit: www.cspg.org/university_outreach.html