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Recovery or Extraction
Roughly 500 km2 of the 140,000 km2 oil sands deposit in Northern Alberta is currently undergoing surface mining activity.
This is about 3 per cent of total oil sands surface area or 20 per cent of oil sands reserves.
Oil sands within 75 m of the surface are mined using electric and hydraulic shovels with a capacity of 45 m3 and trucks that can carry up to 400 tons of ore.
Trucks move the oil sand to a cleaning facility where it is mixed with hot water and diluent (naphthanic, parafanic) to separate the bitumen from the sand.
Sand, water, fine clays and minerals, or tailings, are separated from the bitumen and diluent and sent to tailings ponds where the sand settles.
The diluted bitumen can be piped to an upgrader on site, if one has been built in conjunction with the mine. Currently in Alberta, four facilities in the Fort McMurray area and one near Fort Saskatchewan, near Edmonton upgrade about 54 per cent of Alberta's crude bitumen production. The remainder is sent to upgraders and refineries throughout North America.
About two tonnes of oil sands must be dug up, moved and processed with 2 to 4 barrels of water to produce one barrel of synthetic crude oil (SCO).
In situ recovery is used for bitumen deposits buried too deeply - more than 75 m - for mining to be practical. Most in situ bitumen and heavy oil production comes from deposits buried more than 350-600 m below the surface.
Steam, solvents or thermal energy make the bitumen flow to the point that it can be pumped by a well to the surface.
Cyclic steam stimulation (CSS) and steam-assisted gravity drainage (SAGD) are effective in situ recovery methods.
No tailings ponds are required for in situ methods of recovery. Sand remains in the ground; only bitumen is removed. An average of 0.5 barrels of water is used to produce one barrel of synthetic crude oil (SCO).
Canada's largest in situ bitumen recovery project is at Cold Lake, Alberta, where deposits are heated by steam injection to bring bitumen to the surface, then diluted with condensate for shipping by pipelines.
New technologies that maximize rates of recovery have been tested, such as pulse technology and vapour recovery extraction (VAPEX). More work is required to make this technology beneficial.
Cold Heavy Oil Production with Sand (CHOPS)
CHOPS allows the deliberate flow of sand into a bitumen well in order to increase the rate of bitumen recovery.
Heavy oil is more viscous than conventional oil but less viscous than bitumen. By introducing sand into the well and producing oil and sand together, the higher viscosity is mitigated by the increased permeability of the deposits - the sand essentially creates wormholes through which the bitumen can flow more easily.
Currently, CHOPS is only employed in the Cold Lake oil sands area.