Another name for oil is “petroleum”, and this gives us a clue as to how it was formed. The word “petroleum” means “rock oil”. Scientists think that petroleum was formed from plants and animals that lived ages ago in and around warm seas that covered much of the earth.
As the plants and animals died, they piled up on the sea bottom. In time, millions of tons of sand and mud covered them. Under pressure, the mud and sand changed to rock.
The plants and animals turned into a dark liquid trapped in the pores of the rocks. When parts of the earth’s crust moved upward, sections of the old sea floor became dry land. Some of the liquid oozed to the surface of the earth and so men came to notice it.
Petroleum, or crude oil, has been used for thousands of years. The ancient Egyptians and Chinese used it as a medicine. In India, it. was burned long before the Christian Era.
But until the middle of the nineteenth century, the only way man got this oil was by collecting it when it seeped naturally from the earth. Sometimes it was skimmed from the surfam of streams or soaked up in rags.
Crude petroleum, as it comes to front the well, is of little use. It must be refined. A distillation process separates the different things nature put into crude oil. In this process, we obtain petrol, kerosene, lubricating oils, fuel oil, and asphalt.
Where Is Oil Found?
Oil reserves are found all over the world. However, some have produced more oil than others. The top oil-producing countries are Saudi Arabia, Russia, the United States, Iran, and China.