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Petroleum also known as crude oil, naturally occurring oily is a bituminous liquid composed of organic chemicals. Petroleum means rock oil, from the Greek petros (rock) and oleum (oil). It occurs in the earth in liquid, gaseous or solid forms. The term is usually restricted to the liquid form, commonly called crude oil but as a technical term it also includes natural gas and the viscous or solid form known as bitumen. Petroleum is a complex mixture of organic liquids consisting of hydrocarbons (compounds composed mainly of hydrogen and carbon with some nitrogen, sulphur and oxygen). Petroleum is formed under the earths surface by the decomposition of marine organisms.
The remains of tiny organisms that live in the sea, that are carried down to the sea in rivers and of plants that grow on the ocean bottom are enmeshed with the fine sands and silts and settle to the bottom in quiet sea basins. Such deposits that are rich in organic materials become the source rocks for the generation of crude oil. The process began millions of years ago and still goes on today. Trapped in fine-grained sediments, the remains are cooked by the heat of the earth to produce oil and gas.
Once the petroleum forms, it flows upwards in the earths crust because it has a lower density than the constituents of the earths crust. When petroleum is trapped, a reservoir of petroleum is formed. Exploration is probably one of the most important steps of producing oil. In order to find oil underground geologists, geophysicists and exploration engineers attempt to search for it so that petroleum-producing companies can drill for it. They must search for a sedimentary basin in which shales rich in organic material have been buried for a sufficient long time for petroleum to form. The petroleum must also have had an opportunity to migrate into porous traps that are capable of holding large amounts of fluid.
The occurrence of crude oil in the earths crust is limited both by these conditions, which must be met simultaneously, and by the time of span of tens of millions to a hundred millions years required for the oils formation. These people have many tools at their disposal such as Jack Ups, Semi-submersibles and Drill ships to assist in identifying potential areas for drilling. Exploration mostly involves luck, with one out of ten drilling becoming commercial successes. When crude oil is located, it is necessary to extract it out of the ground. This is done by drilling.
One of the most exciting engineering achievements in recent decades has been the construction and operation of offshore drilling rigs. The drilling rigs are installed, operated and services on an offshore platform in water up to a depth of several hundred meters. The platform may either float or sit on legs planted on the ocean floor where it is capable of resisting waves, winds and even ice floes in Arctic regions. As in traditional rigs the derrick is basically a device for suspecting and rotating the drill pipe to an end of which is attached to the drill bit.
Additional lengths of drill pipe are added to the drill string as the bit penetrates further and further into the earths crust. The force for cutting into the earth comes from the weigh of the drill pipe itself. Drilling fluid is most of the times used because it cools down the drill and the rock. Also it brings loose chunks of rock up to the surface and it prevents cave in and loss of mad into the formation being drilled. Basically the layout of a drilling operation is this: A suitable place is found for drilling Depending on different depths (assuming its offshore) the correct rig is dispatched.
The rig is set up and a drill pipe is sent down (depending on type of rock) Then drilling fluid is sent down to the drill bit. Oil and gas is collected. Crude oil in its natural form is useless to man so as soon as it is collected it is transported to refineries by pipelines. Once crude oil reaches the refinery it goes through various processes to become many different things. The first process is called distillation; this is where the crude oil is separated for the first time. What happens is the crude oil is heated in turbine furnaces up to 380 degrees Celsius and this actually vaporizes the oil.
It is then put into a distillation tower, also called a functioning tower. A functioning tower is a very tall tower, which has many different levels of condensers. The condensers are set to catch the oil vapour as it rises up the tower. They are set with coolest temperature at the top (40 C) and highest temperature at the bottom (370 C).
The condensers then catch the vapour and turn it back into a liquid but in a much purer state then it was in originally. The oil with the lowest boiling point is petroleum; it contains hydrocarbons of 1 - 4 carbon atoms. The petroleum is pumped out of the tower and turned into liquefied petroleum gas (lpg), also known as propane. It is a gas that has many uses, it is most commonly used to fuel heaters and gas stoves. The next fraction out of the tower is gasoline, which contains hydrocarbons of 5 - 12 carbon atoms. This gasoline is not quite ready to go in your car yet.
So, the refinery pumps it across a catalyst to increase its octane rating and then adds many chemicals to it so it will perform well in a cars engine. After gasoline is Kerosene consisting of 12 - 16 hydrocarbons. Kerosene has a few different uses, it is probably best known as lamp and diesel fuel. But what you might not know is that kerosene is also used to make gasoline, how they use it for gasoline will be explained later. The oil that has a lower boiling point than kerosene is gas oil; it contains hydrocarbons of 15 - 18 carbon atoms. Gas oil is used as heating oil for industries and it is also used to make gasoline.
The next to last oil out of the tower is lubricating oil stock which has the highest boiling point of all the liquids mentioned above. It contains hydrocarbons of 16 - 20 carbon atoms. This is used for lubricating oil in vehicles. The last liquid left at the very bottom of the tower is residue it contains hydrocarbons of more than 20 carbon atoms. It is used to make asphalt and gasoline. Now as mentioned above refineries take kerosene and gas oil and turn them into gasoline.
There are a few different methods, the most widely used is called cracking, because it uses heat and pressure to crack the hydrocarbon molecules. Fluid catalytic cracking is the basic process for making gasoline. First the oil is heated up to 1000 degrees Celsius. Then under low pressure with a catalyst it converts heavy hydrocarbon molecules into smaller ones, which can be used for gasoline. Another popular method is hydro cracking which uses a similar processes as fluid catalytic cracking.
The difference between them is that hydro cracking uses lower heat and much greater pressure. As for the residue that is not turned into asphalt, it is placed in a Coker. In the Coker the refinery uses heat and moderate pressure to breakdown the hydrocarbons into gasoline and a coal like substance used as an industrial fuel. The last thing that a refinery does is take the oil left over from cracking and turns it into a usable fuel.
This method is called Alkylation. The main purpose of this is to get a high-octane fuel such as airplane fuel. Petroleum in its natural form has many limited applications. Thankfully, it can be refined in the way that was explained above and have many more useful products. Petrochemicals derived from petroleum became the source of such chemical products as solvents, paints, plastics, synthetic fibres, soaps and cleansing agents, waxes and jellies, explosives, and fertilisers.
Fuels derived from petroleum power the engines of automobiles, airplanes, ships, tractors, trucks and rockets. Petroleum fuels generate a large portion of the worlds electrical-power supply. Asphalt from petroleum is used to surface roads and high ways. It is also used as a lubricant in a great variety of machines. Some of the products of the crude oil are sold to other refineries that make things such as ammonia, crayons, life preservers, mascara, and yes-even bubble gum can be made from crude oil. Finally I hope that the next time you fill up your car you will think about the process that the oil went through to become gas and maybe you wont feel so bad about paying that high price.
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Research essay sample on Oil And Gas Earths Crust
