Athabasca

ATHABASCA (Athabaska; RU: Атабаска) is the deposit of the bituminous sands within Canada, within the Alberta province, at the headwaters of the Athabasca river. It has been discovered during the 1778. The area is 25.6 thousand square kilometres. It is confined to the zone of the tapering of the quartzous sands of the Lower Cretaceous age on the slope of the Canadian shield (the McMurray and Wabiskaw (formations) suites). The depth of the embedment of the productive stratum is 0-610 metres, the average thickness is 46 metres, in certain places is 90 metres. The collectors are represented by the well-sorted fine-grained sands, mostly by the quartzous ones (95%) with the porosity of 25-30% and high permeability. The saturation by the bitumen is from 2% to 18%, with average value of 7.8% (by mass). The collector is hydrophilic. The reserves of the bitumens (the density is 1012.7-1029.1 kilograms per cubic metre) are 101-128 billion tonnes, of which 12 billion tonnes are at the depth of less than 45 metres. The sands are saturated with oil, contain siliceous resins (24.2%), asphaltenes (19.4%), sulfur (4-5%), nitrogen (10.4%), and coke (18.8%). The viscosity of the oil is from 1 to 500 centipoises. With the increase of the depth of embedment, the content of the paraffin wax within the oil increases, and the density of the oil decreases. There are situated at the south-west from Athabasca the Cold Lake (the reserves of the bitumens are 13.7 billion tonnes, the depth is 300-800 metres, the density is 994 kilograms per cubic metre), Peace River (11.8 billion tonnes, the depth is 500-800 metres, the density is 984 kilograms per cubic metre), Wabiskaw (13.7 billion tonnes, the depth is 150-800 metres, the density is 979 kilograms per cubic metre) deposits.

The development of the Athabasca deposit was conducted during the 1936-47, and has been restarted during the 1967. The extraction of the bituminous sands is conducted by 2 companies, which use the rotary excavators with productive capacity of up to 100 thousand tonnes per day; the transportation of the rock mass into the processing plant is performed by the belt conveyors. At the plants, the sands are processed with water at the temperature of 70 degrees Celsius with chemical additives; the consumption of the water is 4 cubic metres per 2 tonnes of the oil-bearing sand. The process of the purification of the sands lasts 4-5 minutes. They obtain 1 barrel of the oil (0.159 cubic metres) from 2 tonnes of sand. At the plant of the "Canadian Oil" company, they produce the synthetic oil with the density of 835 kilograms per cubic metre (7900-8600 tonnes per day), elemental sulfur (350 tonnes per day), coke (260 tonnes per day), and fuel gas. They extract from the wastes the titanium minerals and zircon (up to 690 thousand tonnes per year). With this technology, the extraction of the bitumens from the rock mass is 92%. There is constructed within the deeply embedded part of the layer the underground mine with the retreat mining (clearing) workings within the limestones, which are underlying the productive layer. In association with it, there is constructed the third enterprise for the processing of the sands, with productive capacity of approximately 19 thousand tonnes of oil per day. Besides this, there work within the Alberta province approximately 20 experimental enterprises of various companies, which are researching the most economical methods for the extraction and processing of the bituminous sands, namely, the borehole extraction with the usage of the microbiological methods, horizontal drilling, combustion within the layer, electrical heating, and so on. By the end of the 80-ies, there is planned the increase of the extraction of the oil up to 30 million tonnes per year.