Oil sands production has more than doubled from 600,000 barrels per day (bbl/d) in 2000 to a projected 1.3 million bbl/d in 2009.  Development of the oil sands has made Canada the No. 1 foreign supplier of oil to the US.

In one of the three scenarios developed for a recent IHS/Cambridge Energy Research Associates study, oil sands production reaches 6.3 million bbl/d by 2035 and Canada accounts for 37 percent of US oil imports, up from 19 percent in 2008.

However, oil sands have become a source of contention because their production process is among the more carbon-intensive of oil supply sources.

Oil sands exploration incorporates both mining (“conventional” methods) and in-situ (“non-conventional”) production methods. Mining involves excavation of the bitumen-rich sand using open pit mining methods. This is the most efficient method of extraction when there are large deposits of bitumen with little overburden.

In-situ methods involve processing the oil sand deposit so that the bitumen is removed while the sand remains in place. These methods are used for oil sands that are too deep to support surface mining operations to an economical degree.

Bitumen has to be removed from the sands using either open pit mining or in-situ methods. In the mining method, once the oil sands are excavated the bitumen needs to be extracted from the sands. This is achieved by using a four-step process: conditioning, separation, secondary separation, and froth treatment. Oil sands companies use slightly different separation and froth treatments.

The bitumen also has to be upgraded to synthetic crude oil before it can be refined into common petroleum products such as gasoline and kerosene.

The most common in-situ extraction method is steam-assisted gravity drainage (SAGD).

SAGD involves the drilling of two horizontal wells, one at the bottom of the formation and another about five meters above it. The upper well injects steam into the reservoir. The resulting heat melts the bitumen, which allows gravity to assist it to flow to the lower well, and the bitumen is pumped to the surface.

SAGD is cheaper than cyclic steam stimulation (CSS), the second most common method, allows very high oil production rates and recovers up to 60 percent of the oil.

In the CSS method, the well is put through cycles of steam injection, soak, and oil production. First, steam is injected into a well, at a temperature of 300 degrees Celsius, for a period of several weeks or months. The well is allowed to sit for several days to let heat enter the oil sands. The hot bitumen is then pumped out of the well, which may take weeks. Recovery factors are around 20 to 25 percent, but the cost of injecting the steam is high.

The vapor extraction process (VAPEX) is similar to SAGD, but instead of steam, hydrocarbon solvents are injected into the upper well to dilute the bitumen and allow it to flow. It’s much more energy efficient than steam injection and some partial upgrading of the bitumen to crude oil occurs right in the sands. This method is new and more expensive than the above but oil companies are experimenting with it.

SAGD, CSS and VAPEX aren’t mutually exclusive. Some wells go through a CSS cycle to condition the formation before the SAGD production method is used. Some companies are also starting to combine VAPEX and SAGD to improve recovery rates and decrease energy costs

Toe-to-heel air injection (THAI) is a very new and experimental method where a vertical air injection well is combined with a horizontal production well. This process ignites the bitumen and creates a vertical wall of fire, moving from the “toe” of the horizontal well toward the “heel.”

The heavier oil components are burned and the lighter components are driven into the production well, where they are pumped out. In addition, the heat from the fire upgrades some of the heavy bitumen into lighter oil within the formation. The THAI has the advantage of not requiring energy to create steam.

The Cold Flow production process involves the pumping out of the bitumen without heat, often using specialized pumps called progressive cavity pumps. This method only works well in areas where the bitumen is fluid enough to pump. It is most commonly used in Venezuela, but also in parts of the Athabasca-Wabasca region and the southern part of the Cold Lake region. This is the cheapest method but only recovers about 5 to 6 percent of the bitumen.

Several years ago, Canadian oil companies discovered that if the sand filters are removed from the wells, and as much sand as possible is produced with the oil, the production rates improved considerably. This technique became known as Cold Heavy Oil Production with Sand (CHOPS).

Research showed that pumping out sand opened wormholes in the sand formation, allowing more oil to reach the borehole. The advantage of this method is better production rates and recovery (about 10 percent). The disadvantage is the problem of disposing the large quantity of sand.

In each of the above methods, the bitumen that’s pumped to the surface is in the form of a bitumen-rich froth. This froth is processed through a stripper, which removes the air bubbles and moves the bitumen to froth storage tanks. The sand particles in the froth settle to the bottom and are pumped to the tailings processing system.

According to the IHS/CERA study, total “well-to-wheels” greenhouse gas emissions from oil sands–from extraction and processing through combustion of its refined products–are approximately 5 percent to 15 percent higher than the average crude oil processed in the US. But emissions from oil sands can be higher, lower, or on par with other crude oils processed in the US.

All sources of crude oil emit 70 to 80 percent of their total well-to-wheels emissions from the combustion of refined products, such as gasoline. The difference in total carbon emissions from oil sands to that of other crude oil sources occurs mainly in the extraction and processing phases.