CRUDE OIL

What is crude oil?

When you drive your vehicles or cook something in the kitchen, do you ever think about the energy powering those things?

The energy you use for these purposes comes from fossilfuels, which formed over millions and millions of years from the remains of organisms that lived a long time ago and thus it is a liquid fuel located underground. It is extracted through drilling. Crude oil is a base component of transport fuel, plastics, chemicals, and petroleum products. Crude oil that is found accumulated in various porous rock formations in earth’s crust and is extracted for burning as fuel or for processing into chemical products.

Composition and properties

It is comprised of hydrocarbons, organic compounds and small amounts of metal.  Between 50% and 97% of oil is hydrocarbons. Between 6% and 10% of it is nitrogen, oxygen, and sulphur. Less than 1% is metals such as copper, nickel, vanadium, and iron. Hydrocarbons are usually the primary component of crude oil. It is a mixture of comparatively volatile liquid hydrocarbons but it also contains some nitrogen, oxygen and sulphur. Their composition can vary from 50%-97% depending on the type of crude oil and how it is extracted. Almost all crude oil ranges from 82 to 87 percent carbon by weight and 12 to 15 percent hydrogen by weight.

Paraffins, naphthenes and aromatics are the important hydrocarbons in crude oil. Among them, paraffin is the most common hydrocarbons; certain liquid paraffins are the major constituents of gasoline (petrol) and are therefore highly valued. Naphthenes are an important part of all liquid refinery products, which include cyclohexane and cyclopropane, which are a group of cyclic aliphatic hydrocarbons. Aromatics generally constitute only a small percentage of most crudes. The most common aromatic in crude oil is benzene, a popular building block in the petrochemical industry.

Because it is a mixture of such widely varying constituents and proportions, its physical properties also vary widely. In appearance, the black gold is usually black or dark brown (although it may be yellowish, reddish, or even greenish). The most important physical property is specific gravity (i.e., the ratio of the weight of equal volumes of a crude oil and pure water at standard conditions). Substances lighter than water, such as crude oil, would receive measurements less than 1. Liquids lighter than water, such as oil, have API (American Petroleum Institute) gravities numerically greater than 10. On the basis of their API gravity, crude oils can be classified as heavy, medium, and light.

Crude Oil Formation

 Crude oil is created through the heating and compression of organic materials over a long period of time. Most of the oil we extract today comes from the remains of prehistoric algae and zooplankton whose remains settled on the bottom of an Ocean or Lake. Over time this organic material combined with mud and was then heated to high temperatures from the pressure created by heavy layers of sediment. The layer upon layer of microscopic bacteria formed due to the steady accumulation of dead plant and animal forms.

They were covered by layers of silt, sand and other dead organisms, which forced them ever deeper under the surface of the ocean. As the depth of their burial grew deeper, the pressure upon their bodies increased and the heat surrounding them rose as well. All of these factors combined to convert their bodies into oil, or natural gas, depending upon the variety of biomass concerned, the temperature of heat and the level of pressure. The intense pressure heated the remains underground over millions of years. It first became a waxy substance called kerogen. It became liquid oil after more pressure and heat. Oil is a non-renewable resource. It would take millions of years for new oil to be created when this supply is gone.

Uses of Crude Oil

It is used for numerous purposes but it first has to be refined or separated into usable petroleum products.

We get gasoline, diesel fuel, kerosene, plastics, and even asphalt from refined crude oil. Petroleum products can also be used where we don’t expect either. It can be used in the production of synthetic fibres, sunscreen, medications, hairbrushes, cosmetics, and even your smart phone and sunglasses. It is also used in chemicals, such as fertilizer, perfume, insecticides, soap, and vitamin capsules. Oil is the base for plastics used in everything from heart valves to plastic bags. It is used in carbon fibre in aircraft, PVC pipes etc.

Extraction

The most common method of extraction is drilling. Geologists will first identify a section of land they believe has oil flowing beneath it. The places where oil is present are identified using different methods such as satellite imagery, gravity meters, and magnetometers. Once a steady stream of oil is found, underground the drilling can begin. Drilling is not an overly complicated process however a standard method has been developed to provide maximum efficiency.

The first step of the process involves drilling into the ground in the exact location where the oil is located. Once a steady flow has been identified at a particular depth beneath the ground a perforating gun is lowered into the well. A perforating gun has explosive charges within it that allow for oil to flow through holes in the casing. Once the casing is properly perforated a tube is run into the hole allowing the oil and gas to flow up the well. To seal the tubing a device called a packer is run along the outside of the tube. Finally a structure called Christmas tree is placed which allows oil workers to control the flow of oil from the well.

Environmental impact

The black gold takes a very long time to form but only a short amount of time to use. Researchers suggest that at the rate we’re going, the supply of black gold available on Earth will run out in about 30 years!

Oil can pollute water extensively. Just 1 litre of oil can contaminate 1 million litres of water.  Oil pollution harms animals and insects, prevents photosynthesis in plants, disrupts the food chain, and takes a long time to recover. Additionally, when we burn crude oil products, such as using gas in our cars, we are putting that oil in places like the atmosphere in other forms, like greenhouse gases.

See also Climate change