Petroleum

Petroleum petro + oleum which means rock + oil, also known as crude oil Is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights, and other organic compounds, that are found in geologic formation beneath the Earths surface. Most versatile among the Fossil Fuels (Petroleum, Coal, and Natural Gas).

Non-renewable energy for it needs millions of years before it can be formed.

Thick, black, gooey liquid found way down in the ground, usually between layers of rock.

Origins

It was formed from the remains of tiny sea plants and animals that died millions of years ago. When the plants and animals died, they sank to the bottom of the oceans. Here, they were buried by thousands of feet of sand and silt. Over time, this organic mixture was subjected to enormous pressure, and heat as the layers increased. The mixture changed, breaking down into compounds made of hydrogen and carbon atoms--hydrocarbons. Finally, an oil-saturated rock-much like a wet household sponge was formed.

All organic material does not turn into oil. Certain geological conditions must exist within the oil-rich rocks. There must be a trap of non-porous rock that prevents the oil from seeping out, and a seal (such as salt or clay) that keeps the oil from rising to the surface. Under these conditions, only two percent of the organic material is transformed into oil.

A typical petroleum reservoir is mostly sandstone or limestone in which oil is trapped. The oil in it may be as thin as gasoline or as thick as tar.

Petroleum is called a nonrenewable energy source because it takes millions of years to form. We cannot make new petroleum reserves.

CompositionIn its strictest sense, petroleum includes only crude oil, but in common usage it includes both crude oil and natural gas. Both crude oil and natural gas are predominantly a mixture of hydrocarbons. Under surface pressure and temperature conditions, the lighter hydrocarbons methane, ethane, propane and butane occur as gases, while the heavier ones from pentane and up are in the form of liquids or solids. However, in the underground oil reservoir the proportion which is gas or liquid varies depending on the subsurface conditions, and on the phase diagram of the petroleum mixture. An oil well produces predominantly crude oil, with some natural gas dissolved in it. Because the pressure is lower at the surface than underground, some of the gas will come out of solution and be recovered (or burned) as associated gas or solution gas. A gas well produces predominately natural gas. However, because the underground temperature and pressure are higher than at the surface, the gas may contain heavier hydrocarbons such as pentane, hexane, and heptane in the gaseous state. Under surface conditions these will condense out of the gas and form natural gas condensate, often shortened to condensate. Condensate resembles gasoline in appearance and is similar in composition to some volatile light crude oils.

The proportion of light hydrocarbons in the petroleum mixture is highly variable between different oil fields and ranges from as much as 97% by weight in the lighter oils to as little as 50% in the heavier oils and bitumens.

The hydrocarbons in crude oil are mostly alkanes, cycloalkanes and various aromatic hydrocarbons while the other organic compounds contain nitrogen, oxygen and sulfur, and trace amounts of metals such as iron, nickel, copper and vanadium. The exact molecular composition varies widely from formation to formation but the proportion of chemical elements vary over fairly narrow limits as follows:[4]Four different types of hydrocarbon molecules appear in crude oil. The relative percentage of each varies from oil to oil, determining the properties of each oil.[3]Most of the world's oils are non-conventional.[5]Crude oil varies greatly in appearance depending on its composition. It is usually black or dark brown (although it may be yellowish or even greenish). In the reservoir it is usually found in association with natural gas, which being lighter forms a gas cap over the petroleum, and saline water which, being heavier than most forms of crude oil, generally sinks beneath it. Crude oil may also be found in semi-solid form mixed with sand and water, as in the Athabasca oil sands in Canada, where it is usually referred to as crude bitumen. In Canada, bitumen is considered a sticky, tar-like form of crude oil which is so thick and heavy that it must be heated or diluted before it will flow.[6] Venezuela also has large amounts of oil in the Orinoco oil sands, although the hydrocarbons trapped in them are more fluid than in Canada and are usually called extra heavy oil. These oil sands resources are called unconventional oil to distinguish them from oil which can be extracted using traditional oil well methods. Between them, Canada and Venezuela contain an estimated 3.6trillion barrels (57010^9m3) of bitumen and extra-heavy oil, about twice the volume of the world's reserves of conventional oil.Petroleum is used mostly, by volume, for producing fuel oil and gasoline (petrol), both important "primary energy" sources.[8] 84% by volume of the hydrocarbons present in petroleum is converted into energy-rich fuels (petroleum-based fuels), including gasoline, diesel, jet, heating, and other fuel oils, and liquefied petroleum gas.[9] The lighter grades of crude oil produce the best yields of these products, but as the world's reserves of light and medium oil are depleted, oil refineries are increasingly having to process heavy oil and bitumen, and use more complex and expensive methods to produce the products required. Because heavier crude oils have too much carbon and not enough hydrogen, these processes generally involve removing carbon from or adding hydrogen to the molecules, and using fluid catalytic cracking to convert the longer, more complex molecules in the oil to the shorter, simpler ones in the fuels.

Due to its high energy density, easy transportability and relative abundance, oil has become the world's most important source of energy since the mid-1950s. Petroleum is also the raw material for many chemical products, including pharmaceuticals, solvents, fertilizers, pesticides, and plastics; the 16% not used for energy production is converted into these other materials. Petroleum is found in porous rock formations in the upper strata of some areas of the Earth's crust. There is also petroleum in oil sands (tar sands). Known reserves of petroleum are typically estimated at around 190km3 (1.2 trillion (short scale) barrels) without oil sands,[10] or 595km3 (3.74 trillion barrels) with oil sands.[11] Consumption is currently around 84million barrels (13.410^6m3) per day, or 4.9km3 per year.

Advantages Highly compact portable source of energy used for most forms of mechanical transportation.

Excellent source of organic molecules for building plastics, medicines, rubber, fiber, etc.

Can withstand high heats without breakdown making it useful as lubricants like motor oil and grease

Residuals make excellent surface for asphalt roads and waterproof roofing materials

Certain components make excellent solvents for paint, industrial use etc.

Other components (propane, butane) make excellent compact source of portable cooking fuel and heating in areas that do not have infrastructure for natural gas delivery.

Natural gas is used to make fertilizers used in agriculture and household detergents

Compared to most other fuel sources it is still one of the most economical -in other words the costs to produce it are relatively cheap compared to other energy sources.

Production of oil has much less impact and a smaller footprint on the earth surface than production of coal from strip mining

If not for the discovery of oil, all whales would likely be extinct, because they were the primary source of lamp oil for lighting before oil, and are still recovering from hunting in the 1800's.

The oil industry has been a source of much advanced technology and many new products that have changed our lives for the better.

During WW2 oil produced in Texas was the major source of fuel supply for the Allied Forces and without that advantage over both the Germans and Japanese, the world might look very different today. At that time the US was the major supplier of oil in the world.

Natural gas wells are the world's supply of helium gas.

Oil refining produces the world's supply of elemental sulphur as a byproduct, used for many industrial applications.

Disadvantages Oil is a carbon based fuel and the primary way it is used is to burn it, releasing more than its weight in CO2 because of the added oxygen. CO2 is a greenhouse gas and is expected by most scientists to be a cause of global warming.

We are running out. Estimates vary from 50 to 150 years before we run out of oil. This is impossible to predict, but most major oil companies have been failing to discover new reserves equal to the amount of oil they are producing for the last few years.

Much of the remaining oil in the world is in politically unstable areas including Africa, Middle East, Russia, and parts of Southeast Asia.

Wars get fought over oil, and wars are won with oil (WW2) so it can be a very negative influence on relations between nations.

Oil must be transported in ever increasing quantities. Pipelines are one common method but where no pipeline exists oil can become 'stranded', in other words there is no way to get it to market. The natural gas in northern Alaska is a good example of this since there is no gas pipeline the oil companies must pump natural gas back into the wells.

The other transport problem with oil is from the inherent dangers of supertankers. Oil spills do serious environmental damage that takes decades to recover from. While oil spills do occur naturally, and have over time, the effects are often catastrophic for the area affected. Oil does break down naturally from biological and chemical decay, but it takes time.

Our consumption of oil is increasing at the same time our production is falling. The world is currently consuming 83 million barrels of oil per day. We aren't producing that much.

Many oil producing areas are subject to severe weather and this can interupt production. Last year's hurricanes are an example. Production will not be restored until well into this year.

Oil does contain some cancer causing compounds, benzene is one of those.

Volatile components of oil and natural gas can contribute to smog.

Some additives put into gasoline to improve its smog fighting qualities have leaked out of underground tanks at gas stations and polluted ground water with hazardous chemicals. This type of pollution is very hard to remove.

Drilling for oil is getting more difficult and expensive because we are now drilling as deep or deeper than 20,000 feet to find new reserves.

Because of the price cyclicity in the oil industry the industry is discovering that it may soon have a serious shortage of trained workers. The average age in the industry is about 50 years old. New entrants are not coming into the field for several reasons. The oil industry is going to be challenged to keep producing at the current rate with fewer employees available.

Some oil is now being strip mined in the form of tar sands. This will be very hard to restore these areas.

Sulphur in oil ends up in refined fuels and contributes to air pollution.

http://en.wikipedia.org/wiki/Petroleumhttp://www.typesofenergy.co.uk/petroleum-energy-source.htmlhttp://www.kidzworld.com/article/1423-fossil-fuel-energyhttp://lsa.colorado.edu/summarystreet/texts/petroleum.htm