How Oil and Natural Gas Form

Oil and natural gas, generically classified together as petroleum products, are found deep within the earth in many parts of the world, with many more yet to be discovered. Massive drilling operations are set up throughout the world by companies such as Western Pipeline Corporation in locations that have been determined to be good candidates for containing this naturally occurring, high demand commodity. Most consumers are aware that their vehicles and the natural gas used in their homes rely on the availability of petroleum such as oil and natural gas, but countless other products utilize petroleum as a raw material or a component of production. Many household items such as make up, pain relievers and compact discs are comprised at least partly of petrochemicals, which are chemicals derived from petroleum.

The fact that petroleum products are an integral part of many things we do in our every day lives is widely known, but the origin of petroleum products is a subject with which many people are unfamiliar. Petroleum literally means “rock oil,” from the Latin terms petra, meaning rock, and oleum, which means oil. What surprises many people is that oil is actually formed from the remains of small organisms, such as algae, plankton and vegetation which lived tens or hundreds of millions of years ago in oceans and lakes. When these ancient organisms pass away, their remains settle on the bottoms of the oceans or lakes, and are covered by mud and sediment. The presence of oxygen with time helps organisms decay, but the small percentage of these dead organisms that will go on to form oil become compressed into oxygen deprived mud and rock. Over thousands of years, this layer of mud and sediment containing the organic matter is covered by many more layers created in the same manner, with pressure and heat exerted on the original layer becoming increasingly intense. Eventually, the sediment under intense pressure forms a solid rock, with the organic matter still contained within it. This rock is called the source rock.

Intense pressure and heat exerted on the source rock helps to turn the organic matter into a form of oil or natural gas. Oil is forced from the source rock into reservoir rocks, which are porous rocks such as sandstone that have room inside to “soak up” the oil and hold it. In order for oil to collect in concentrated area from which it can be extracted by humans, movements in the earth must enclose the porous rocks containing the oil with non-porous rock through which the oil does not pass. You may think of this impermeable rock, called “cap” or “trap” rock, as being the “walls” and “ceilings” of the area of oil accumulation.

Through this process, oil and natural gas form deep within the earth over millions of years.