Pilots target bitumen

Dec. 21, 2009
Various companies put on hold several Alberta oil sands projects during 2009 in reaction to the global recession and lower crude prices, but other projects have continued including two proposed pilots in carbonate formations in the West Athabasca oil sands area.

Various companies put on hold several Alberta oil sands projects during 2009 in reaction to the global recession and lower crude prices, but other projects have continued including two proposed pilots in carbonate formations in the West Athabasca oil sands area.

Alberta's Energy Resources Conservation Board in its June reserves overview estimated that potential recoverable bitumen from Alberta's carbonate formations is 37.7 billion bbl compared with 207.6 billion bbl from Cretaceous sands.

Including mining projects, its estimate for total ultimate recovery potential from all oil sands deposits in Alberta is 315 billion bbl of which it categorizes 177 billion bbl as established. Cumulative oil sands production at yearend 2008 was 6.4 billion bbl.

In Alberta, the carbonate formations are older and underlie the Cretaceous sands. In the West Athabasca area (previously called the Wabasca deposit), the carbonates containing bitumen include the Devonian Nisku and Grosmont formations.

Some potential methods for recovering the bitumen from carbonates could involve cold solvents, cyclic steam stimulation, steam-assisted gravity drainage, solvent injection with SAGD, and electrical heating.

Pilots

ERCB's most recent approved pilot for the carbonates is for the Sunshine Oilsands Ltd. Harper acreage. Sunshine's Harper area extends over 619 contiguous sections (about 640 acres/section) and the company says a consulting firm assessed 128 sections and determined that this area contains more than 2 billion bbl of bitumen in place with a potential 536 million bbl recoverable.

Sunshine drilled, logged, and cored four wells in the area during its 2007-08 winter work program. The company plans to complete a single well, one-cycle CSS pilot during winter 2009 to demonstrate reservoir response to thermal and chemical stimulation of the 9-12 gravity bitumen at a 550-m depth. It plans no permanent installations and will remove all equipment because the area is in a winter access only, Caribou Zone.

The company notes that production from the carbonates on its Harper, Portage, Muskwa, Goffer, and Ells leases could eventually exceed 400,000 b/d.

Laricina Energy Ltd. is another company that received ERCB approval for a pilot in the carbonates. ERCB approved a pilot on Laricina's Saleski acreage in mid-2009, although still pending is a Laricina filed amendment for adding solvents to its SAGD scheme. The company notes that circulating a solvent such as propane can mobilize bitumen in advance of steam chamber growth and help lower steam requirements.

Laricina holds 60% interest in the 6,944 acres on its Saleski lease, while Osum Oil Sands Corp. holds the remaining 40%.

The 1,800 b/d Saleski pilot is within the West Athabasca oil sands area about 100 km southwest of Fort McMurray. The main target reservoir is within the Grosmont C and D formation that lies at an average 325-m depth.

Laricina describes the Grosmont formation as a dolomitized, shallow marine, and tidal flat carbonate complex that has extensive vertical fracturing, karsting, and a high-permeability reservoir with potential bitumen thickness greater than 50 m.

The company plans to start construction of the pilot in first-quarter 2010 with steam injection starting at yearend 2010 and solvent addition starting in 2012.

Its proposed pilot will have a small central processing facility including conventional diluent treating and solvent recovery systems, a single well pad with three SAGD well pairs, an access corridor, borrow pits, camp site, sumps and source water and disposal wells; and a storm water retention pond.

If the pilot succeeds, Laricina plans to install initially a 10,000 b/d commercial project and start production in 2013. Several 20,000-60,000 b/d development phases would then follow during 25 years with total bitumen production eventually reaching 270,000 b/d.

It estimates that the area contains more than 2.3 billion bbl of recoverable bitumen.

The company said a recently completed cold-solvent field test in Saleski successfully mobilized bitumen.

Other projects

Two other companies that have large leaseholds in carbonate prospects in Alberta are Shell Canada Ltd. and Husky Energy Inc.

Shell acquired its Grosmont leases in 2006 and has carried out appraisal and exploration activities. The company proposes to test an in situ bitumen upgrading process involving electric heaters that would product lighter crude and leave heavier crude components in the formation.

Husky estimates that the carbonates on its Saleski acreage contain 32 billion bbl of bitumen in place but said it has reduced its work on this acreage until economic conditions improve.

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