Introduction
Aberta's oil sands contain the biggest known reserve of oil in the world. An estimated 1.7 to 2.5 trillion barrels of oil are trapped in a complex mixture of sand, water and clay. The most prominent theory of how this vast resource was formed suggests that light crude oil from southern Alberta migrated north and east with the same pressures that formed the Rocky Mountains. Over time, the actions of water and bacteria transformed the light crude into bitumen, a much heavier, carbon rich, and extremely viscous oil. The percentage of bitumen in oil sand can range from 1% -20%. The oil saturated sand deposits left over from ancient rivers in three main areas, Peace River, Cold Lake and Athabasca. The Athabasca area is the largest and closest to the surface, accounting for the large-scale oil sands development around Fort McMurray.
Since the 1920's, open pit mining has been central to oil sands development. Mine equipment from the early years was scaled up significantly when large commercial operations started to come on line. The first large scale commercial operation, Great Canadian Oil Sands (now Suncor Energy), introduced German manufacturer O&K bucket wheels from the coal mining industry when they opened in 1967. Syncrude Canada Limited opened in 1978 and introduced gigantic draglines 60 times as large as the bucket on display from Bitumount, the first commercial oil sands plant. These large machines were connected to the processing plant by a system of conveyor belts. Today, large trucks and shovels have replaced draglines and bucket wheels as a more selective, and cost effective way to mine oil sands. The process begins by clearing trees, draining and storing the overburden and then removing this top layer of earth to expose the ore body. The equipment must be durable and strong enough to withstand extreme climate and abrasive oil sand. Mining never stops, the trucks and other equipment work day and night, every day of the year. Planning is an essential and continuous part of the process.
Geologists, surveyors and mine engineers play a considerable role in the mine planning process before any heavy equipment is introduced. The mine plan must commit to return the area to it's former environmental condition. G.P.S. is used extensively to pinpoint mining areas.
Dr. Karl Clark, a scientist working for the Alberta Research Council, developed and patented the hot water extraction technique. Building on earlier experimentation by Sidney Ells and others which used hot water to separate oil from oil sands, Dr. Clark's work brought the process to a commercial scale. Oil sand is mixed with hot water creating a slurry. Early methods used large tumbler drums to condition the slurry. Today, hydro transport pipelines are used to condition and transport the oil sand from the mine to the extraction plant. The slurry is fed into a separation vessel where it separates into three layers - sand, water and bitumen. The bitumen is then skimmed off the top to be cleaned and processed further. Secondary recoveries are made with the middling zone of the separation vessels to return the smaller quantities of bitumen that would otherwise flow to the settling ponds. Ph levels and temperature are key variables in the process.
About 80% of the oil sands in Alberta are buried too deep below the surface for open pit mining. This oil must be recovered by in situ techniques. Using drilling technology, steam is injected into the deposit to heat the oil sand lowering the viscosity of the bitumen. The hot bitumen migrates towards producing wells, bringing it to the surface, while the sand is left in place ("in situ" is Latin for "in place"). Steam Assisted Gravity Drainage (SAGD) is a type of in situ technology that uses innovation in horizontal drilling to produce bitumen. In situ technology is expensive and requires certain conditions like a nearby water source. Production from in situ already rivals open pit mining and in the future may well replace mining as the main source of bitumen production from the oil sands.
Challenges facing in situ process are efficient recoveries, management of water used to make steam, and co-generation of all (otherwise waste) heat sources to minimize energy costs. Other methods of in situ recovery look promising, and are in research stages of development.
The oil in oil sand is called bitumen, a complex hydrocarbon made up of a long chain of molecules. In order for bitumen to be processed in refineries, this chain must be broken up and reorganized. Unlike smaller hydrocarbon molecules bitumen is carbon rich and hydrogen poor. Upgrading means removing some carbon while adding additional hydrogen to make more valuable hydrocarbon products. This is done using four main processes: coking removes carbon and breaks large bitumen molecules into smaller parts, distillation sorts mixtures of hydrocarbon molecules into their components, catalytic conversions help transform hydrocarbons into more valuable forms and hydro treating is used to help remove sulphur and nitrogen and add hydrogen to molecules. The end product is synthetic crude oil, which is shipped by underground pipelines to refineries across North America to be refined further into jet fuels, gasoline and other petroleum products.
It must be noted that some of the oil companies pipe their bitumen south in diluted form for upgrading at other refineries. Others produce either a single high quality synthetic crude oil or multiple petroleum products to suit market feedstock demand.
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Once the final product is shipped by pipeline to refineries, an environmental footprint remains. This can include open pit mine holes, process water dykes and emissions. Minimizing the impact to the environment begins by understanding the complexity of eco-systems. This information is used to help develop reclamation plans that determine how to return productive areas, to a self- sustaining, productive state, as required by all lease agreements. An important part of this process is state of the art environmental monitoring programs and communication with stakeholders including environmental groups and aboriginal people. This is an area of ongoing research activity, and while improvements in environmental stewardship have been made, huge challenges remain. Protecting the environment is a shared responsibility involving industry, government and consumers of hydrocarbon products. These products include gasoline, fuel for our homes, and petroleum chemical products like plastics, fleece and even toothpaste!