Иностранный язык (английский) - для технических специальностей

     Shale oil and tar sands are the most prevalent form of petroleum found in the world. Reserves of these two sources are more than 500 times as great as the world’s combined proved reserves of crude oil. Because of the high cost of converting shale oil and tar sands into usable petroleum products, however, relatively little of the material is produced commercially. An industry to make oil products from tar sands has been started in Canada, and Venezuela is looking at the prospects of developing the vast reserves of heavy oil in its Orinoco River basin. Nevertheless, by the year 2000, the quantity of oil products produced from these two raw materials will be small compared with the total production of conventional crude oil.