CRUDE OIL MANUFACTURING PROCESSES

CRUDE OIL MANUFACTURING PROCESSES
The following are the important stages in the manufacture of crude oil
FORMATION OF CRUDE OIL: Crude oil is created through the heating and compression of organic materials over a long period of time. Most of the oil we extract today comes from the remains of prehistoric algae and zooplankton whose remains settled on the bottom of an Ocean or Lake. Over time this organic material combined with mud and was then heated to high temperatures from the pressure created by heavy layers of sediment. This process, known as diagenesis, changes the chemical composition first into a waxy compound called kerogen and then, with increased heat, into a liquid through a process called catagenesis.
EXPLORATION : this is the process of searching for rocks associated with oil or natural gas deposits, and involves geophysical prospecting and/or exploratory drilling. Geologists will first identify a section of land they believe has oil flowing beneath it. There are a number of ways this can be accomplished, the most frequently used methods are satellite imagery, gravity meters, and magnetometers
DRILLING AND WELL DEVELOPMENT occurs after exploration has located an economically recoverable field, and involves the construction of one or more wells from the beginning (called spudding) to either abandonment if no hydrocarbons are found, or to well completion if hydrocarbons are found in sufficient quantities. The most common method of crude oil extraction is drilling.. Once a steady stream of oil is found, underground the drilling can begin. Drilling is not an overly complicated process however a standard method has been developed to provide maximum efficiency. The first step of the process involves drilling into the ground in the exact location where the oil is located. Once a steady flow has been identified at a particular depth beneath the ground a perforating gun is lowered into the well. A perforating gun has explosive charges within it that allow for oil to flow through holes in the casing. Once the casing is properly perforated a tube is run into the hole allowing the oil and gas to flow up the well. To seal the tubing a device called a packer is run along the outside of the tube. The last step involves the placement of a structure called a Christmas tree which allows oil workers to control the flow of oil from the well. Oil can also be extracted from oil sands, often called tar sands. Oils sands are typically sand or clay mixed with water and a very viscous form of crude oil known as bitumen.
After the extraction of crude oil, scientific research has also provided the basic technigues involved in the processing or refining of crude oil in order to obtain different fractional products that are specifically used for various purposes. Such refining processes include:

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1. Fractional distillation: Modern distillation involves pumping oil through pipes in hot furnaces and separating light hydrocarbon molecules from heavy ones in downstream distillation towers – the tall, narrow columns that give refineries their distinctive skylines.

The Pascagoula Refinery’s refining process begins when crude oil is distilled in two large Crude Units that have three distillation columns, one that operates at near atmospheric pressure, and two others that operate at less than atmospheric pressure, i.e., a vacuum.

During this process, the lightest materials, like propane and butane, vaporize and rise to the top of the first atmospheric column. Medium weight materials, including gasoline, jet and diesel fuels, condense in the middle. Heavy materials, called gas oils, condense in the lower portion of the atmospheric column. The heaviest tar-like material, called residuum, is referred to as the “bottom of the barrel” because it never really rises.This distillation process is repeated in many other plants as the oil is further refined to make various products.In some cases, distillation columns are operated at less than atmospheric pressure (vacuum) to lower the temperature at which a hydrocarbon mixture boils. This “vacuum distillation” (VDU) reduces the chance of thermal decomposition (cracking) due to over heating the mixture. Using the most up-to-date computer control systems, refinery operators precisely control the temperatures in the distillation columns which are designed with pipes to withdraw the various types of products where they condense. Products from the top, middle and bottom of the column travel through these pipes to different plants for further refining.

2. Cracking: Since the marketplace establishes product value, our competitive edge depends on how efficiently we can convert middle distillate, gas oil and residuum into the highest value products. At the Pascagoula Refinery, we convert middle distillate, gas oil and residuum into primarily gasoline, jet and diesel fuels by using a series of processing plants that literally “crack” large, heavy molecules into smaller, lighter ones.

Heat and catalysts are used to convert the heavier oils to lighter products using three “cracking” methods: fluid catalytic cracking (FCC), hydrocracking (Isomax), and coking (or thermal-cracking). The Fluid Catalytic Cracker (FCC) uses high temperature and catalyst to crack 86,000 barrels (3.6 million gallons) each day of heavy gas oil mostly into gasoline. Hydrocracking uses catalysts to react gas oil and hydrogen under high pressure and high temperature to make both jet fuel and gasoline. Also, about 58,000 barrels (2.4 million gallons) of lighter gas oil is converted daily in two Isomax Units, using this hydrocracking process.

We blend most of the products from the FCC and the Isomaxes directly into transportation fuels, i.e., gasoline, diesel and jet fuel. We burn the lightest molecules as fuel for the refinery’s furnaces, thus conserving natural gas and minimizing waste.

In the Delayed Coking Unit (Coker), 98,000 barrels a day of low-value residuum is converted (using the coking, or thermal-cracking process) to high-value light products, producing petroleum coke as a by-product. The large residuum molecules are cracked into smaller molecules when the residuum is held in a coke drum at a high temperature for a period of time. Only solid coke remains and must be drilled from the coke drums.

Modifications to the refinery during its 2003 Clean Fuels Project increased residuum volume going to the Coker Unit. The project increased coke handling capacity and replaced the 150 metric-ton coke drums with new 300 metric-ton drums to handle the increased residuum volume.

The Coker typically produces more than 6,000 tons a day of petroleum coke, which is sold for use as fuel or in cement manufacturing.

Combining

While the cracking processes break most of the gas oil into gasoline and jet fuel, they also break off some pieces that are lighter than gasoline. Since Pascagoula Refinery’s primary focus is on making transportation fuels, we recombine 14,800 barrels (622,000 gallons) each day of lighter components in two Alkylation Units. This process takes the small molecules and recombines them in the presence of sulfuric acid catalyst to convert them into high octane gasoline.

3. Treating (Removing Impurities)

The products from the Crude Units and the feeds to other units contain some natural impurities, such as sulfur and nitrogen. Using a process called hydrotreating (a milder version of hydrocracking), these impurities are removed to reduce air pollution when our fuels are used.

Because about 80 percent of the crude oil processed by the Pascagoula Refinery is heavier oils that are high in sulfur and nitrogen, various treating units throughout the refinery work to remove these impurities.

In the RDS Unit’s six 1,000-ton reactors, sulfur and nitrogen are removed from FCC feed stream. The sulfur is converted to hydrogen sulfide and sent to the Sulfur Unit where it is converted into elemental sulfur. Nitrogen is transformed into ammonia which is removed from the process by water-washing. Later, the water is treated to recover the ammonia as a pure product for use in the production of fertilizer.

The RDS’s Unit main product, low sulfur vacuum gas oil, is fed to the FCC (fluid catalytic cracker) Unit which then cracks it into high value products such as gasoline and diesel.

4. Reforming

Octane rating is a key measurement of how well a gasoline performs in an automobile engine. Much of the gasoline that comes from the Crude Units or from the Cracking Units does not have enough octane to burn well in cars.

The gasoline process streams in the refinery that have a fairly low octane rating are sent to a Reforming Unit where their octane levels are boosted. These reforming units employ precious-metal catalysts – platinum and rhenium – and thereby get the name “rheniformers.” In the reforming process, hydrocarbon molecules are “reformed” into high octane gasoline components. For example, methyl cyclohexane is reformed into toluene.

The reforming process actually removes hydrogen from low-octane gasoline. The hydrogen is used throughout the refinery in various cracking (hydrocracking) and treating (hydrotreating) units.

Our refinery operates three catalytic reformers, where we rearrange and change 71,000 barrels (about 3 million gallons) of gasoline per day to give it the high octane cars need.

Blending: A final and critical step is the blending of our products. Gasoline, for example, is blended from treated components made in several processing units. Blending and Shipping Area operators precisely combine these to ensure that the blend has the right octane level, vapor pressure rating and other important specifications. All products are blended in a similar fashion.

Quality Control

In the refinery’s modernly-equipped Laboratory, chemists and technicians conduct quality assurance tests on all finished products, including checking gasoline for proper octane rating. Chevron’s patented performance booster, is added to gasoline at the company’s marketing terminals, one of which is located at the Pascagoula Refinery.

The discovery of crude oil and its refinery has led to the following advantages :
Source of foreign exchange  for nations: While just about every country in the world depends on oil, not all countries produce it. The top five oil producing countries such as Saudi Arabia, Russia, United States, Iran, and China are major exporters of oil across the world and by so doing it earns them foreign exchange and thereby enhances the economic condition of the country.
Development of  suitable fuels for different vehicle and machinery :  The bus which has an engine works with petrol. The train is driven by the power of coal. Tractors are driven by kerosene. This is possible only because of the application of science.
Synthesis of Plastics: many plastics are made from products of crude oil.
Production of asphalts : the heaviest fractions of crude oil are used for surfacing of road.



CONCLUSION
From the above, it is clear that science is playing an important part in our everyday life.is now entering a period where the great discoveries mostly cannot be made with out some sort of financial backing for the equipment and research time. This means that there is a real chance for major nations losing ground in the sciences if they do not make the conscientious effort to invest in research and development. President Obama made a telling point in saying that innovation was the key to “winning the future.” In an increasingly competitive global market it is the country that can harness innovation and technology that will be the most successful economically. Basical labor is something that can gain value one day and lose it the next but the possibilites and new markets created by science and invention are eternal.

. Science affects us all, every day of the year, from the moment we wake up, all day long, and through the night. Your digital alarm clock, the weather report, the asphalt you drive on, the bus you ride in, your decision to eat a baked potato instead of fries, your cell phone, the antibiotics that treat your sore throat, the clean water that comes from your faucet, and the light that you turn off at the end of the day have all been brought to you courtesy of science. The modern world would not be modern at all without the understandings and technology enabled by science.

To make it clear how deeply science is interwoven with our lives, just try imagining a day without scientific progress.

Science has improve the quality of life at many different levels — from the routine workings of our everyday lives to global issues. Science informs public policy and personal decisions on energy, conservation, agriculture, health, transportation, communication, defense, economics, leisure, and exploration. It's almost impossible to overstate how many aspects of modern life are impacted by scientific knowledge. Here we'll discuss just a few of these examples. You can investigate:

Indeed, true that science has added tremen­dously to the comforts and conveniences of mankind. Unless one is an ascetic, one has no reason to reject the things science offers. By conquering time and distance science has brought mankind together and so far made life richer. By inventing medicines it has made our day-to-day existence relatively free from disease, and has, indeed, added to our length of life.