A bit of history
A bit of history
Centuries ago, civilizations around the globe were aware of petroleum (derived from the Medieval Latin words petr, or rock, and oleum, or oil) but did not immediately identify it as a source of energy. In the Western world, wood was the fuel of choice for heating and cooking for centuries. As forest reserves were depleted, coal was the next energy source to be tapped, along with whale oil, which was used primarily as a lubricant and fuel for lamps. The invention of the coal-fired steam engine in 1765 sparked the desire to build different, bigger and more powerful machines. This progress, along with plentiful coal resources, ultimately drove the industrial revolution and a move to urbanization.
Electricity entered the picture with Benjamin Franklin’s 1752 invention of the lightening rod, followed by the electric battery in 1800 and the first use of electricity in industrial motors in 1837. Progress in electricity was moving rapidly, but it was the invention in 1860 of the first internal combustion engine using coal gas, a mixture of gasses produced by distilling bituminous coal, that foreshadowed the beginning of great change. Just a few years later, in 1864, the invention of an engine that used gasoline as a fuel launched what quickly became an era of innovation and invention with an attendant demand for oil.
Petroleum became a major industry in the U.S. after oil was first discovered in Pennsylvania in 1859. Another important milestone in U.S. oil production was reached in 1901, when a well at Spindletop Hill, a salt dome oil field in Beaumont, Texas, struck oil, and the Texas Oil Boom was underway.
The circle of life
Crude oil (petroleum), as well as natural gas and coal, are called fossil fuels because they are the byproducts of fossilized plant, animal and diatomic (made of two atoms) sea life that lived 300 to 400 millions of years. Most fossil fuels are thought to have originated in ancient oceans and other bodies of water. Scientists have theorized that when this plant and diatomic sea life died, it became part of the sediment at the bottom of the lakes and oceans. Over a period of 50 to 100 million years, these fossilized remains were buried by sediment and rock layers. The pressure and heat from this increasingly heavy burden formed the fossilized remains into a dark organic layer called kerogen. Much later, that kerogen ultimately turned into natural gas and crude oil underneath layers of salt, silt, rock and earth.
Petroleum & natural gas products
A similar process occurred on land where fossilized plant and animal life formed peat (partially decayed vegetation) and eventually natural gas, crude oil, and coal within a type of rock called shale.
All about hydrocarbons
Crude oil is a liquid containing complex, naturally occurring hydrocarbons (a compound of hydrogen and carbon). The product of decomposed matter, hydrocarbons come in different lengths and constructs, from straight chains to chains with branches to complete rings. When broken down over time, hydrocarbons form crude oil or natural gas. Depending on the pressure and temperature in which they exist, hydrocarbons may be gaseous (consisting of one to four carbon atoms per molecule), liquid (containing five to 16 carbon atoms per molecule) semisolid or solid (containing 20 carbon atoms per molecule).
Crude oil is a mixture of a large number of different hydrocarbons; the most commonly found molecules are alkanes (paraffins), cycloalkanes (naphthenes) and aromatic hydrocarbons. Each type of crude oil has a unique mix of molecules, which dictates its color and viscosity. For example, crude oil is liquid, but it may also have gaseous or solid compounds. Light oils stay in a liquid state even at low temperatures. Crude oil varies in color, ranging from clear or yellow to green or black, and in viscosity, from watery to almost solid.
Oil’s myriad uses in our everyday lives
Today, oil is found in underground reservoirs around the world, often near coal deposits, and is the major fuel used on the planet. It fuels everything from our cars and airplanes to our farm and industrial machinery. Oil is used to make a wide variety of materials, such as the lubricant oils we use in our cars and other machinery, as well as tires, plastics and chemicals.
All crude oil, extracted in its raw state, has no direct commercial application or use until it is refined. Once refined, it is stored in barrels, which hold approximately 42 U.S. gallons, or about 159 liters.
Producing oil
In the U.S., crude oil is produced in more than 30 states and off the coasts of Alaska, California, and Louisiana. For many years we extracted oil primarily using conventional methods, which relied on traditional rigs and vertical drilling to access the reserves and on pump jacks to bring it to the surface for collection.
Over time, the conventional resources in the U.S. became depleted, but advances in drilling and extracting technologies now enable producers to tap into unconventionally produced resources. These resources, previously inaccessible, contain vast amounts of oil and natural gas that are trapped in a type of porous rock called shale. It is these unconventional resources that are driving the nascent North American oil and gas boom.
The map below identifies the major North American shales. Over the course of the last decade, oil-rich shale formations have been actively developed in Texas, including the Eagle Ford shale in South Texas and the Permian basin in West Texas and southeastern New Mexico, as well as the enormous Bakken shale in North Dakota and several others shown on the map below. During the decade, unconventional shale formations with vast oil and natural gas resources have been actively developed in Texas, including the Eagle Ford shale in South Texas, and a multitude of shales in the Permian basin in West Texas and southeastern New Mexico. Also of great significance are the Marcellus in the mid-Atlantic states, the enormous Bakken shale in North Dakota and Montana and expanding into Canada, and several others shown on the map below. The Bakken, Permian and Eagle Ford are primary oil plays, while the Marcellus is primarily a natural gas play.
Source: Tortoise
Crude, sweet and sour
There are many different types of crude oil, and they have different values. Crude oil is classified by sulfur content, density measurement and location of production.
| Type of oil | Amount of sulfur | Predominant North American production |
|---|---|---|
| Sweet | Low < 0.5% | Central U.S. |
| Sour | Higher > 0.5% | Canada |
When it comes to type, crude oil is identified as sweet or sour. Sweet crude is crude with a less than 0.2% sulfur content, and is the predominant type of oil currently being produced in the central part of the U.S. Domestic production of sweet crude has increased as a result of the oil shale boom. Sour crude is crude oil with at least a 0.5% sulfur content (or more), and within North America, is found predominantly in Canada. It is attractive because it yields distillates (a liquid product condensed from a vapor) that are in high demand, although it is more expensive to refine.
From field to pump
Regardless of where it winds up, all crude oil first has to be refined – a process that uses chemicals, catalysts, heat and pressure to free usable products from impurities. These products are used to make a wide range of products stretching far beyond gasoline, diesel and jet fuel. In fact, gasoline accounts for less than half of the products made from a barrel of crude oil in U.S. refineries, while a third ends up as jet and diesel fuel. The remaining crude may be refined without changing its molecular structure and used to make fuel oil and lubricating oil.
In the U.S., five areas are called Petroleum Administration for Defense Districts, or PADDs. They were created during World War II to help organize the allocation of petroleum products, including gasoline and diesel fuel. Still used today for data collection purposes, PADDs help the regulatory agencies monitor regional petroleum product supplies and track usage patterns and product movement throughout the country.
Breaking down the barrel
We get more than fuel out of a barrel of oil, as indicated by the blue band in the illustration below. Other processes use chemicals that alter the molecular structure of oil (and natural gas liquids) to make petrochemicals, which become the feedstock (raw materials) used to make a host of other products, ranging from soap and fertilizer to epoxies and explosives, from synthetic fibers and adhesives to paints and even medicine.
Liquefied petroleum gas (more commonly known as propane or butane) is flammable gas used as a fuel in heating appliances and vehicles, and increasingly as an aerosol propellant and refrigerant. Ethylene and propylene are refined oil petrochemicals, which are used in making the plastics that are everywhere in our homes, cars, businesses, hospitals and industries. Aromatic fluids are another byproduct of crude oil that are used to make products ranging from dyes and synthetic detergents to the materials used in shoes, fabrics, furniture and beverage containers and even cell phones. It’s hard to imagine a world without the oil-derived products we use and enjoy every day.
Source: Energy Information Administration
