A fraction of crude oil is a mixture of chemicals in the crude oil that have similar boiling points. A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
The crude oil is evaporated inside a furnace before entering the fractionating column where its vapours condense at different temperatures. A petrochemical is a substance made from crude oil using chemical reactions.
For example, ethene is produced from crude oil. It is used as feedstock to make poly ethene , a polymer. Today, petroleum is found in vast underground reservoirs where ancient seas were located. Petroleum reservoirs can be found beneath land or the ocean floor. Their crude oil is extracted with giant drilling machines.
Crude oil is usually black or dark brown, but can also be yellowish, reddish, tan, or even greenish. Variations in color indicate the distinct chemical compositions of different supplies of crude oil. Petroleum that has few metals or sulfur, for instance, tends to be lighter sometimes nearly clear. Petroleum is used to make gasoline, an important product in our everyday lives.
It is also processed and part of thousands of different items, including tires, refrigerators, life jackets, and anesthetics. When petroleum products such as gasoline are burned for energy, they release toxic gases and high amounts of carbon dioxide, a greenhouse gas.
Petroleum even exists far below the deepest wells that are developed to extract it. However, petroleum, like coal and natural gas, is a non-renewable source of energy. It took millions of years for it to form, and when it is extracted and consumed, there is no way for us to replace it.
Oil supplies will run out. Some experts predict peak oil could come as soon as Finding alternatives to petroleum is crucial to global energy use, and is the focus of many industries. Formation of Petroleum The geological conditions that would eventually create petroleum formed millions of years ago, when plants, algae, and plankton drifted in oceans and shallow seas.
These organisms sank to the seafloor at the end of their life cycle. Over time, they were buried and crushed under millions of tons of sediment and even more layers of plant debris. Eventually, ancient seas dried up and dry basins remained, called sedimentary basins. Oxygen was almost completely absent in these conditions, and the organic matter began to transform into a waxy substance called kerogen. With more heat, time, and pressure, the kerogen underwent a process called catagenesis , and transformed into hydrocarbons.
Hydrocarbons are simply chemicals made up of hydrogen and carbon. Different combinations of heat and pressure can create different forms of hydrocarbons. Some other examples are coal, peat , and natural gas. Sedimentary basins, where ancient seabeds used to lie, are key sources of petroleum. More than oil deposits have been discovered in the massive Niger Delta basin, and they comprise one of the most productive oil fields in Africa.
Chemistry and Classification of Crude Oil The gasoline we use to fuel our cars, the synthetic fabrics of our backpacks and shoes, and the thousands of different useful products made from petroleum come in forms that are consistent and reliable.
However, the crude oil from which these items are produced is neither consistent nor uniform. Other elements such as nitrogen about 0. The way molecules are organized in the hydrocarbon is a result of the original composition of the algae, plants, or plankton from millions of years ago. The amount of heat and pressure the plants were exposed to also contributes to variations that are found in hydrocarbons and crude oil.
Due to this variation, crude oil that is pumped from the ground can consist of hundreds of different petroleum compounds. It is almost always necessary to refine crude oil in order to make useful products. Classification Oil is classified according to three main categories: the geographic location where it was drilled, its sulfur content, and its API gravity a measure of density.
Classification: Geography Oil is drilled all over the world. However, there are three primary sources of crude oil that set reference points for ranking and pricing other oil supplies: Brent Crude, West Texas Intermediate, and Dubai and Oman. Brent Crude is a mixture that comes from 15 different oil fields between Scotland and Norway in the North Sea.
These fields supply oil to most of Europe. WTI supplies much of North America with oil. Dubai crude, also known as Fateh or Dubai-Oman crude, is a light, sour oil that is produced in Dubai, part of the United Arab Emirates. The nearby country of Oman has recently begun producing oil. Dubai and Oman crudes are used as a reference point for pricing Persian Gulf oils that are mostly exported to Asia.
Sulfur in crude oil can corrode metal in the refining process and contribute to air pollution. Petroleum with more than 0. The API has established accepted systems of standards for a variety of oil- and gas-related products, such as gauges, pumps, and drilling machinery.
The API has also established several units of measurement. API gravity is a measure of the density of petroleum liquid compared to water. Light oils are preferred because they have a higher yield of hydrocarbons. Heavier oils have greater concentrations of metals and sulfur, and require more refining. Petroleum Reservoirs Petroleum is found in underground pockets called reservoirs. Deep beneath the Earth, pressure is extremely high.
Petroleum slowly seeps out toward the surface, where there is lower pressure. It continues this movement from high to low pressure until it encounters a layer of rock that is impermeable. The petroleum then collects in reservoirs, which can be several hundred meters below the surface of the Earth. Oil can also be contained by stratigraphic traps. Different strata, or layers of rock, can have different amounts of porosity. Crude oil migrates easily through a layer of sandstone, for instance, but would be trapped beneath a layer of shale.
Geologists, chemists, and engineers look for geological structures that typically trap petroleum. During the process, a small explosion is set off. Sound waves travel underground, bounce off of the different types of rock, and return to the surface. Sensors on the ground interpret the returning sound waves to determine the underground geological layout and possibility of a petroleum reservoir.
The amount of petroleum in a reservoir is measured in barrels or tons. An oil barrel is about 42 gallons. This measurement is usually used by oil producers in the United States. Oil producers in Europe and Asia tend to measure in metric tons. There are about 6 to 8 barrels of oil in a metric ton. The conversion is imprecise because different varieties of oil weigh different amounts, depending on the amount of impurities. Crude oil is frequently found in reservoirs along with natural gas.
In the past, natural gas was either burned or allowed to escape into the atmosphere. Now, technology has been developed to capture the natural gas and either reinject it into the well or compress it into liquid natural gas LNG. LNG is easily transportable and has versatile uses. Extracting Petroleum In some places, petroleum bubbles to the surface of the Earth. In parts of Saudi Arabia and Iraq, for instance, porous rock allows oil to seep to the surface in small ponds.
However, most oil is trapped in underground oil reservoirs. The total amount of petroleum in a reservoir is called oil-in-place. These petroleum liquids may be too difficult, dangerous, or expensive to drill. Drilling can either be developmental, exploratory, or directional. Drilling in an area where oil reserves have already been found is called developmental drilling. Prudhoe Bay, Alaska, has the largest oil reserves in the United States.
Developmental drilling in Prudhoe Bay includes new wells and expanding extraction technology. Drilling where there are no known reserves is called exploratory drilling. McCarthy struck oil 38 times in the s, earning millions of dollars. Directional drilling involves drilling vertically to a known source of oil, then veering the drill bit at an angle to access additional resources. Accusations of directional drilling led to the first Gulf War in Iraq accused Kuwait of using directional drilling techniques to extract oil from Iraqi oil reservoirs near the Kuwaiti border.
Iraq subsequently invaded Kuwait, an act which drew international attention and intervention. After the war, the border between Iraq and Kuwait was redrawn, with the reservoirs now belonging to Kuwait. Oil Rigs On land, oil can be drilled with an apparatus called an oil rig or drilling rig. Offshore, oil is drilled from an oil platform. Primary Production Most modern wells use an air rotary drilling rig, which can operate 24 hours a day.
In this process, engines power a drill bit. A drill bit is a cutting tool used to create a circular hole. The drill bits used in air rotary drilling rigs are hollow steel, with tungsten rods used to cut the rock. Rather than using drills, crude oil is extracted from oil sands through strip mining or a variety of other techniques used to reduce the viscosity of the oil. This process can be far more expensive than traditional drilling and is found in high abundance only in Canada and Venezuela.
As oil demand continues to rise, and reserves become depleted, oil sands could provide one of the last viable methods for extracting crude oil from the Earth. While just about every country in the world depends on oil, not all countries produce it. It is important to note that the term production here refers to crude oil extracted from oil reserves. At the current rate of consumption it is estimated that worldwide reserves will become extinguished by
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