- The Earth’s surface, millions of years ago, was covered with more water than what it has today and living in this were billions of tiny plants and animals.
- When these plants and animals died, they fell to the ocean floor and piled up sand from eroding rocks and mud covered them up.
- These layers of sand and mud were heavy and this weight turned them into sedimentary rocks.
- Heat from the earth and the weight of the rocks caused the dead plants and animals to compress into oil. Once the oil is formed, it slowly moves up through pores in the rocks. However in some cases, rocks without any pores leaves oil trapped underground.
- Oil is found in different parts of the world. The places where oil is extracted are called oil fields. More than half of the world’s oil is produced in the Middle East. To get to the oil, a company must first drill down to it. A rig is set up to support the drill. Then a well is drilled into the ground until the oil is reached. If the oilfield is in the sea, then offshore rigs are used.
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