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.

Petroleum drill bits can be 36 centimeters 14 inches in diameter. As the drill bit rotates and cuts through the earth, small pieces of rock are chipped off.

A powerful flow of air is pumped down the center of the hollow drill, and comes out through the bottom of the drill bit. The air then rushes back toward the surface, carrying with it tiny chunks of rock. Geologists on site can study these pieces of pulverized rock to determine the different rock strata the drill encounters. When the drill hits oil, some of the oil naturally rises from the ground, moving from an area of high pressure to low pressure.

It is also one of the most dangerous, and a piece of equipment called a blowout preventer redistributes pressure to stop such a gusher.

Pumps are used to extract oil. Most oil rigs have two sets of pumps: mud pumps and extraction pumps. Mud pumps circulate drilling fluid. The petroleum industry uses a wide variety of extraction pumps.

Which pump to use depends on the geography, quality, and position of the oil reservoir. Submersible pumps, for example, are submerged directly into the fluid. A gas pump, also called a bubble pump, uses compressed air to force the petroleum to the surface or well. One of the most familiar types of extraction pumps is the pumpjack , the upper part of a piston pump. A crank moves the large, hammer-shaped pumpjack up and down.

Far below the surface, the motion of the pumpjack moves a hollow piston up and down, constantly carrying petroleum back to the surface or well. Successful drilling sites can produce oil for about 30 years, although some produce for many more decades. Other methods are necessary to extract this petroleum, a process called secondary recovery.

Vacuuming the extra oil out was a method used in the s and early 20th century, but it captured only thinner oil components, and left behind great stores of heavy oil. Water flooding was discovered by accident. In the s, oil producers in Pennsylvania noticed that abandoned oil wells were accumulating rainwater and groundwater. The weight of the water in the boreholes forced oil out of the reservoirs and into nearby wells, increasing their production.

Oil producers soon began intentionally flooding wells as a way to extract more oil. The most prevalent secondary recovery method today is gas drive.

During this process, a well is intentionally drilled deeper than the oil reservoir. The deeper well hits a natural gas reservoir, and the high-pressure gas rises, forcing the oil out of its reservoir.

Oil Platforms Drilling offshore is much more expensive than drilling onshore. It usually uses the same drilling techniques as onshore, but requires a massive structure that can sustain the tremendous strength of ocean waves in stormy seas.

Offshore drilling platforms are some of the largest manmade structures in the world. They often include housing accommodations for people who work on the platform, as well as docking facilities and a helicopter landing pad to transport workers.

The platform can either be tethered to the ocean floor and float, or can be a rigid structure that is fixed to the bottom of the ocean, sea, or lake with concrete or steel legs. More than 70 people work on the platform, in three-week shifts. The platform is meters feet tall and is anchored to the ocean floor. For more on CO 2 emissions from the combustion of hydrocarbon fuels, click here. Fossil Fuels. Nuclear Fuels.

Acid Rain. Climate Change. Climate Feedback. Ocean Acidification. Rising Sea Level. A gasoline pump featuring five octane ratings, represented by the five different numbers on the pump.

Please pardon our regional dialect. April 10th, What are the products and uses of petroleum? June 21, The economics of oil dependence: a glass ceiling to recovery [Online]. June 29, It is a fossil fuel that took millions of years to form and there is a finite amount of petroleum available.

Once all the petroleum is used in the world it will be gone for good. As society has advanced, and because of the harmful effects of petroleum and that it is a finite resource, society has come up with alternatives to petroleum. These alternatives include wind, solar, and biofuels. Wind power uses wind turbines to harness the power of the wind to create energy.

Solar power uses the sun as an energy source, and biofuels use vegetable oils and animal fat as a power source. Petroleum is a fossil fuel that is used widely in our day-to-day lives. In its refined state, it can be turned into gasoline, kerosene, fuel, and other uses, which as a society we use in transportation, lighting, heat, and more.

Petroleum is a finite material that once used up will not be able to be replaced. Its use is also harmful to the environment, as well as its extraction process. It is for these reasons that the use of alternative energy sources is being explored and implemented, such as solar and wind energy. Renewable Energy. Your Privacy Rights. To change or withdraw your consent choices for Investopedia. At any time, you can update your settings through the "EU Privacy" link at the bottom of any page. These choices will be signaled globally to our partners and will not affect browsing data.

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Your Practice. Popular Courses. Table of Contents Expand. What Is Petroleum? Understanding Petroleum. Types of Petroleum. Pros and Cons of Petroleum. How Is Petroleum Formed?

What Is Petroleum Used For? Is Petroleum Toxic to Humans? Is Petroleum Renewable? What Are Alternatives to Petroleum? The Bottom Line. Petroleum is used as fuel to power vehicles, heating units, and machines, and can be converted into plastics and other materials. The extraction and processing of petroleum, and thus, its availability, is a major driver of the world's economy and global politics. Petroleum is a finite product that was created over millions of years.

Once it is used up there will be no way to replace it. Due to the harmful effects and limited supply of petroleum, other energy sources are becoming prominent, such as solar and wind. Cons Carbon emissions are toxic to the environment. Transportation can damage the environment. Extraction process is harmful to the environment. Article Sources.