A Shell worker with a handful of black, sticky oil sand at the Muskeg River mine
By Sarah Shenker
BBC News, Calgary
As the massive yellow truck approaches the digger, it manoeuvres into position and honks its horn, signalling its readiness to receive a payload of 400 tonnes of black, oily sand.
Already, another truck has stopped some 100m away, ready to take its turn ferrying oil sand from the mine face to the crushers for the first step in its processing into oil.
At just over 620 tonnes, the Caterpillar 797B is the largest truck in the world, with tyres as tall as two men and as heavy as a bus. The digger is seven storeys high and its shovel can lift 100 tonnes a scoop.
"Driving one of these is like driving a pick-up truck," says Cindy Blanchard, 40, who works at Shell's Muskeg River mine in the province of Alberta.
She works 12-hour shifts, days and nights, feeding the 24/7, 365-day oil sands industry which had been booming.
These truck drivers can earn more than C$100,000 a year
Oil prices reached an all-time record of $147 (£99) a barrel in July but the subsequent drop amid worries over the global economy has been steep.
Industry insiders are keen to take the long view but there is no doubt lower prices are threatening to put a brake on the tar sands bonanza.
The industry had an uncertain start in the late 1950s and early 1960s - a cheap and efficient extraction method was elusive enough to prompt plans to use a nuclear bomb to access deep reserves.
But technological advances coupled with rising demand and prices for oil pushed production to 1.2m barrels a day, more than double what it was in 2000.
Economically recoverable reserves have now been put at 173bn barrels, placing Canada second only to Saudi Arabia in global oil reserves.
"It's a world-class resource, with 300 to 400 years of production left in it at current rates," says Martyn Griggs, oil sands manager with the Canadian Association of Petroleum Producers (CAPP) in Calgary.
Deputy Premier Stevens sees a bright future for Alberta
There are three major players at the moment - Suncor, Syncrude and a consortium led by Shell - but more foreign investors and consortiums have piled in.
They have helped make the oil sands one of the biggest capital investment projects in the world, averaging C$20bn ($15.8bn; £10.7bn) a year over the past few years, and with more than C$100bn ($79bn; £53.6bn) projects announced for the next 10 years.
"The potential is vast," says Don Thompson, president of the industry body, the Oil Sands Developers Group, and a Syncrude employee for 29 years.
One in six Albertans are employed in the oil industry, which accounts for a third of provincial revenue. The province has a budget surplus, and an unemployment rate of about 3%.
"It is the economic engine of Alberta and of Canada," says Alberta's conservative Deputy Premier Ron Stevens.
"At this time of global economic turmoil, the one shining economic light in this country is the oil sands," he says.
It has undoubtedly been a tumultuous year for the industry.
As oil prices dropped from highs of over $140 (£95) a barrel to under $50, falling at one point as low as $40, about C$40bn worth of future projects have been put on hold in recent months.
Many future oil sands projects had been counting on oil prices of $70-80 a barrel, although established producers would still make a reasonable profit at $50 a barrel, says the CAPP's Mr Griggs.
The industry takes a long-term view, he says: "When you are investing some C$20bn a year, you're not looking at today's oil prices."
Two or three years ago, $50 a barrel would have been a good price.
Mr Thompson of the Oil Sands Developers Group says the delays are understandable.
"But the energy demands of the world will continue to grow and inevitably, sources of conventional crude will continue to decline... The oil sands will continue to be developed," he says.
Mining oil sands is still a tricky business.
Each grain of oil sand is made up of grain of sand surrounded by an envelope of water, with an outer layer of bitumen - a type of heavy crude oil.
To reach the oil-rich sand, operators have to clear-cut the boreal forest of northern Alberta, drain wetlands and remove hundreds of metres of peat-rich topsoil and overburden.
It takes two tonnes of oil sand - a mix of bitumen, sand, clay and water - to make one barrel of oil.
Oil sands lie about 100m deep so trees and overburden - a clay, silt and gravel mix - is cleared first.
Mined oil sand is crushed and mixed with hot water to form slurry. Bitumen floats to the top and can be extracted.
The leftover water, clay, sand and residual bitumen, known as tailings, is pumped into large man-made lakes.
Bitumen is upgraded on site or piped further south in Alberta or to the US, where it is refined into fuels etc.
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