When the well reaches a pool, oil usually rises up the well because of its density difference with water beneath it or because of the pressure of expanding gas trapped above it.

当井和一个水池相接时，油通常会从井里上升，因为它与井下的水的密度不同，或者因为停留在它上方的膨胀气体的压力。

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Gas pressure gradually dies out, and oil is pumped from the well.

气体压力逐渐消失，石油从井里泵出。

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In the BP example, the oil in the well is under pressure, and so it wants to emerge from the hole that created the well.

在BP的例子里，井下的石油承受着很大压力，因此它非常想从井洞里逃出来。

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The city is also host to the world's largest gas-stimulation project in development: 240 million cubic feet of Tengiz natural gas is injected daily into the reservoirs to loosen up oil and boost well pressure.

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The well is gushing because of the pressure the oil is under in its reservoir 4, 300 metres below the sea bed.

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