Talking Energy Talk

In situ oilsands development

When one thinks of Alberta’s oilsands industry, it can be easy to picture what once was boreal forest disrupted by giant open-pit mines and vast ponds of toxic waste. In reality, oilsands mining—which is environmentally regulated both provincially and federally— represents access to only a fraction of the resource, which is second in the world only to Saudi Arabia.

Of the 172 billion barrels of oilsands reserves in Alberta, less than 20 per cent is shallow enough to be recoverable using surface mining. Once the target reservoir is deeper than about 75 metres underground, economics and technology dictate that operators must drill to produce from it.

“Eighty per cent of the oilsands will developed in situ [Latin for “in place”], which accounts for 97.5 per cent of the total oilsands surface region of Alberta,” says the Canadian Association of Petroleum Producers (CAPP).

While the majority of current production comes from mining—about 64 per cent of 1.25 million barrels per day in 2009—that is certain to change in the future as in situ projects proliferate.

In its natural state, bitumen will not flow to a wellbore. So the major challenge of recovering bitumen from depth is to overcome its high viscosity to allow it to flow to the wellbore. The most common production method for in situ projects in the Athabasca region of northern Alberta is a technique known as steam assisted gravity drainage (SAGD). Horizontal well pairs are drilled parallel to each other in a bitumen-bearing reservoir, with one located near the top and the other near the bottom. Steam is continuously injected into the top well, creating a steam chamber between the wells where the bitumen is heated, becoming less viscous. The bitumen has the consistency of molasses when heated.

Gravity causes the oil to flow to the bottom well, where it is pumped to the surface.

SAGD is a popular method today, but it has been commercial for less than a decade. Since the 1980s, two major companies have been producing oilsands in situ using a different method, known as cyclic steam stimulation—Imperial Oil at Cold Lake, and Shell Canada at Peace River. Steam is injected down a single wellbore, followed by a soak time, and then the same wellbore is used to pump up fluids. Producing about 140,000 barrels per day, Imperial’s Cold Lake facility remains Alberta’s largest in situ oilsands installation.

While groups such as CAPP indicate that the environmental footprint of in situ operations is smaller than that of surface mining, others disagree.

“Preliminary indicators show greenhouse gas and sulphur emissions are higher for in situ than for mining. Some in situ projects also have higher total water use intensities than the average for mining. And the land use impacts… are serious, too,” says Simon Dyer, oilsands program director with the Pembina Institute. However, he adds that the solutions could come from within the industry itself.

“There are ways to improve,” says Dyer. “Were industry to employ its own best practices, they could not only improve their environmental performance, but their reputation as well.”

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