The Story of Oil

19 The Story of Oil Oil-a liquid that drives our cars, heats our homes and provides much of our electricity. It's found in every imaginable product. It's often referred to as “ liquid gold" . In its refined state, it's called petroleum, which literally means “ rock oil" . The long journey of oil, from the source below the earth's outer crust to the fuel tank of a car, begins in prehistoric times when the earth was covered in water. Small marine life died and fell to the sea bottom, slowly accumulating on the muddy seabed. There was no oxygen in many of the accumulating layers, so the material did not break down completely. This allowed much of the decaying material to change into carbon and hydrogen atoms. This process repeated itself many times over many millions of years. More dead and dying materials accumulated on top of the previous layers, forming new layers in the rock.

After millions of years, the rich seas began to recede. As the earth dried, additional land-based organic material decayed, and went through the same process. All that was needed then was the addition of heat, which came about as the result of pressure exerted on the material by each new layer. Heat and pressure increased over thousands of years as the weight of the layers built up. This changed the material into a gooey substance called kerogen, which later changed into a crude oil. This crude oil began to trickle away from the source rock to varying depths below the surface, until it became trapped in reservoirs where it lay dormant for millions of years. In the 20th century, humans began drilling deep into the earth to find this crude oil. It is now shipped to refineries where the gooey material is transformed into the valuable commodity it is today. Gasoline is still the crown jewel. In fact, half of every barrel of crude oil is turned into gasoline. The remainder is further refined and ends up in many consumer products, completing a process that began long before humans roamed the earth.