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AP® Environmental Science

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Secondary Extraction

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Petroleum is extracted from the earth by drilling. During primary extraction, about 5-15% of the petroleum at that site can be brought to the surface.

What is secondary extraction and why is it necessary?

A

All new oil wells have a significant amount of pressure pushing the oil up. This is greater than the natural pressure and is called secondary.

B

Coal and natural gas have a natural pressure exerted on them. This is called primary extraction. Secondary extraction is extra pressure that must be applied to petroleum to bring it to the surface.

C

As oil is extracted, pressure in the area is reduced and the remaining oil is more difficult to bring to the surface. By injecting fluid like water or brine or a gas like carbon dioxide, pressure can be added that pushes out more of the oil.

D

Secondary extraction is when a second company must be brought in to finish oil extraction because the primary company went bankrupt.

E

Secondary extraction occurs after drilling which is known as primary extraction.