Text 3 The Extraction of Crude Oil and Natural Gas

Crude oil needs to be extracted from deep below the ground by drilling wells and using an oil rig to pump it to the surface. The oil is not located everywhere under the Earth's surface. Usually geologists find it by using explosives underground where they suspect that oil may be present. Geologists use measurements of reflected sound waves from the explosions to help them discover whether oil is present or not. Then they do a test drill breaking through a cap of solid rock. The layer above the oil is a layer of soft rock (chalk or sandstone) and oil. The layer below is porous rock containing salt water. If oil is located, it is pumped to the surface. An oil storage buoy is placed above the location of the drill. If there is a lot of natural gas trapped in a pocket along with the crude oil, a “gusher-type” well develops where the oil gushes to the surface requiring very little pumping. Natural gas is commonly used in houses all over the world. Oil tankers are used to transport the oil.