How Petroleum is Formed

Petroleum is made primarily of mixtures of hydrocarbons, compounds of carbon, and hydrogen. Scientists believe petroleum hydrocarbons come from the remains of tiny animals and plants that lived millions of years ago.

The idea that oil was created from dinosaurs is a myth. Though dinosaurs were huge creatures, there simply weren’t enough of them to create such large amounts of oil.

When tiny organisms die, they sink to the bottom of the sea and are mixed with mud and silt. Over time, hundreds of feet of mud containing the organisms accumulate. Bacteria removes most of the oxygen, nitrogen, phosphorus, and sulfur, leaving mainly hydrogen and carbon. Lack of oxygen keeps the animals and plants from decaying completely.

The partially decomposed organisms create a slimy mass, which is then covered with layers of sediments. Over millions of years, many layers of sediment pile on top of the once-living organisms. The weight of the sediment compresses the mud into a fraction of its original thickness. When the depth of burial reaches about 10,000 feet, heat, time and pressure turn the organisms into different types of petroleum.

Higher temperatures usually produce lighter petroleum. Lower temperatures create a thick material, like asphalt. As the heat continues to alter the substances, gas is often produced. Depending on how much gas is present, sometimes it will stay mixed with the oil and sometimes it will separate. At temperatures above 500 degrees Fahrenheit, the organic matter is destroyed and neither oil nor gas is formed.

The mud and silt become more and more compressed and turn into a rock known as shale. As the mud is being compressed into shale, the oil, gas and saltwater are squeezed out. The fluids move from the original rock, known as the source rock, to a new rock, called a reservoir rock.

About the Author:
Chris Jent is Chief Marketing Officer of Triple Diamond Energy Corporation.Triple Diamond Energy Corporation is an independent producer of oil and natural gas. Located in the Dallas area, the company specializes in acquiring the highest quality prime oil and gas properties.