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Exploration for oil around the Scottish shores has become a very big 1_______. This is an account of how oil is extracted from beneath the North Sea.
To get the oil out, four production problems will be used: huge structures, three made of concrete and one of 2_______, designed to work for 25 years or more. Instead of floating, they are planted firmly on the sea bed and designed to stand up to the worst of sea and weather. From each platform a series of holes is 3_______, some going almost straight down, others drilled at an 4_______ away from the platform so that a large volume of oil can be extracted. The oil does not lie there like a great swimming pool full of black liquid, it is trapped in small spaces between the porous rocks. To get as much as possible out many separate holes have to be drilled.