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Here is a compilation of essays on ‘Petroleum’ for class 6, 7, 8, 9 and 10. Find paragraphs, long and short essays on ‘Petroleum’ especially written for school students.
Essay on Petroleum
Essay Contents:
- Essay on the Introduction to Petroleum
- Essay on the Origin of Petroleum
- Essay on the Properties of Petroleum
- Essay on the Ways for Trapping Petroleum
- Essay on the Prospecting and Drilling of Petroleum
- Essay on the Transportation and Storage of Petroleum
- Essay on the Reserves of Petroleum
- Essay on the Uses of Petroleum
Essay # 1. Introduction to Petroleum:
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Petroleum, the mineral in the greatest demand in modern industry, supplies half the world’s energy requirements. It provides fuel for heat and lighting, lubricants for machinery and raw materials for a number of manufacturing industries.
In comparison with other fuels, such as coal, it has several advantages: it occurs in great abundance; it is easily obtained; it can be cheaply distributed; and above all, it has the widest range of domestic as well as industrial uses. It is often, therefore, referred to as ‘black gold’.
Despite repeated predictions of its rapid exhaustion, world petroleum production increases every year. Scientists and geo- physicists, using modern prospecting equipment such as the gravimeter, magnetometer and seismograph are discovering more and more new oilfields and are greatly widening the world’s known reserves of oil. Many of the most recently discovered fields are deep beneath the sea-floor.
The word petroleum is derived from the Latin words petra, meaning rock, and oleum, meaning oil. It is so called because it is derived from the rocks, where it flows freely in either liquid or gaseous state. It was first used where seepages occurred at the surface. In ancient times the Chinese, who encountered oil in drilling for salt in brine wells, used it as fuel to evaporate the brine.
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The Egyptians used it for embalming the dead before burial. The Bible notes that dark pitch from petroleum residues was used on Noah’s ark to make the wooden vessel waterproof. It was also recorded that tar (bitumen) was employed in cementing bricks in the construction of the Tower of Babylon, and in paving the streets in Mesopotamia.
Petroleum was also mentioned by many Greek and Roman writers who noted its use as lamp fuel and for ointments. In many other parts of the world such as around the Caspian Sea, in Romania, in Burma and in India, oil was often used in lighting, cooking, lubricating and for medical purposes.
But the first man to have really ‘struck oil’ was probably Samuel M. Kier who in 1848 found it by chance in wells on the banks of the Allegheny River of Pennsylvania. He named it after the local Indians as Seneca oil. The shortage of whale oil, then widely used for domestic lighting and for oiling machinery, created a great demand for mineral oil.
The Seneca Oil Company was soon formed for drilling oil. ‘Colonel’ Edwin L. Drake, a retired railway conductor, was sent to Titusville, Pennsylvania (about 80 km/50 miles north of Pittsburgh) to drill for oil. He encountered many setbacks. After two months, on 27 August 1859, drilling to a depth of 21.2 metres (69 ½ft), Drake struck oil.
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It poured at the rate of 10 barrels (1.3 tonnes) a day. This ushered in the great ‘oil rush’, and commercial exploitation of petroleum on a large scale began. Drake, however, died a poor man, though he had made it possible for many oilmen to become rich after him. To commemorate his achievement, a stone monument was erected at the exact spot of his first oil well in the Drake Memorial Park at Titusville.
Essay # 2. Origin of Petroleum:
The origin of petroleum is still not definitely known, though it is generally presumed to be derived from organic material. Analysis of oil samples shows that it is formed from the decomposition by anaerobic bacteria of innumerable small marine plant and animal organisms trapped in sediments as they were deposited on the sea-bed.
Some scientists believe that when an accumulation of sedimentary rocks in the ocean depths is compacted, the pressure generates heat which transforms the decaying matter into tiny droplets of oil. Others think that oil may have formed relatively rapidly after the organisms were trapped in the sediments and that heat or pressure were not necessary to the process.
Oil formation in sedimentary rocks has been going on since the beginning of geological time and is probably continuing today, and unlike many other minerals which require special conditions for their occurrence, oil can be found in many different rocks of various ages and is very widely distributed. Wherever there are areas of marine sedimentary rocks such as mudstone, shale, sandstone or limestone oil may be found in some of the strata.
The oil is trapped in the pore-spaces of the rocks and thus rocks such as sandstone with a high proportion of spaces are most likely to contain oil. Compacted mud and shale have very tiny pore spaces which either prevent the presence of oil or make it very difficult to obtain, e.g. from oil shales, if it is present.
Within porous rocks the oil is capable of migrating in any direction until it is trapped by the presence of a non-porous cap-rock such as a shale or mudstone. When the rocks originally formed under the sea, not only oil was trapped but also sea-water. This also remains in the pore spaces of the rock. Because oil is lighter than water it usually lies above it in the rock. Above the oil are the lightest hydrocarbons forming natural gas.
Thus oil is usually found in a water-oil-gas sequence, though sometimes only gas is found, and no oil exists. When a cap-rock prevents the oil or gas from moving further, either upwards or sideways it is trapped; it cannot move downwards through the heavier water. Oil rarely occurs in igneous rocks, and when it does it is due to migration of oil from sedimentary rocks into interstices such as joints in the igneous rocks.
Essay # 3. Properties of Petroleum:
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Technically speaking, petroleum is an inflammable mixture of oily hydrocarbons with very complex chemical properties. Some crude oils contain other minerals such as sulphur. Crude petroleum varies in colour from amber-green to brownish black. The lighter grades are greenish, have a high hydrogen content but little carbon. The heavier grades are almost black and have a low hydrogen percentage but more carbon.
In terms of specific gravity (i.e. its weight compared with water which is 1), crude petroleum varies from 0.77 to 0.99 and is therefore lighter than water so that it always floats on water. In commercial circles, oil is gauged by hydrometers, whose readings are given in the Baume Scale. Oil that gives a reading of over 30° is classified as light oil, and that lower than 20° is heavy oil.
The modern petroleum industry recognizes three principal grades of crude oil:
i. Paraffin-Base Oil:
This contains a high percentage of the lighter hydrocarbons such as methane and yields the commercially more valued products, e.g. petrol, paraffin and high grade lubricating oils.
ii. Asphalt-Base Oil:
This consists mainly of the heavier hydrocarbons with a viscous, asphaltic base. It is of less commercial significance because it yields little motor-oil during distillation. Much of its residue is in the form of asphalt or bitumen, almost in solid state.
iii. Mixed-Base Oil:
This is an intermediate group with mixed properties of the lighter and heavier oils. It carries a high percentage of naphthene and is graded 20° on the Baume Scale. It is used both for lubricants and fuel oils.
Essay # 4. Ways for Trapping Petroleum:
There are several common ways in which oil can be trapped.
i. Anticlinal Trap:
This is the most common mode of oil occurrence. Rock strata are often subject to folding as a result of earth movements, and are arched up as anticlines or domes. Oil is trapped in the crest of the upfold, usually in the gas-oil-water sequence.
The oil-bearing stratum is a porous layer, e.g. sandstone, through which oil may flow. The oil is prevented from rising or sinking by intervening layers of non-porous strata, e.g. shale. Wells sunk at A will tap oil while wells at B and C would tap gas and water respectively.
ii. Fault Trap:
Earth movements may also cause faulting and porous and non-porous strata may be brought into juxtaposition. The Oil is trapped in a tilted layer of reservoir rock (sandstone) and is prevented from escaping by the cap-rock above (shale).
iii. Salt Plug:
A salt plug is formed when a huge body of rock salt, a rather mobile and weak rock, is subjected to great pressure from above. It pushes upwards through a weakness in the overlying strata to form a steep-sided dome. Oil is trapped around the margins of the salt plug.
iv. Stratigraphic Trap:
Oil may be trapped stratigraphically where it occurs in rocks that, after folding, are eroded down and then subjected to renewed deposition. The layers above the unconformity may be non-porous and thus trap the oil. Where rocks lense-out, oil may also be trapped.
Essay # 5. Prospecting and Drilling of Petroleum:
Since Colonel Drake drilled his first oil well at Titusville in 1859, fortune-seekers all over the world have been hoping to strike oil. Many of them began drilling without making any comprehensive structural studies of the underlying rocks.
Such random drilling is described as wild-catting. Drilling for oil is so expensive, that many who struck no oil went bankrupt. Colonel Drake was fortunate to strike oil at only 21.2 metres (69 ½ ft) for most oil wells are several thousand metres deep, and prospecting and drilling operations can take weeks or months.
One of the world’s deepest wells, in Pecos, Texas, was drilled to a depth of 7,725 metres (25,340 ft), cost US$3 million, over a year’s work and found no oil! Disappointment in oil drilling is not unusual and drilling is a calculated risk. For example, in 1949, an estimated 38,000 wells were drilled in the United States: 60 per cent struck oil, 7 per cent produced natural gas, while the remaining 33 per cent were simply ‘dry holes’.
Once oil is struck, people rush to share the new source of wealth and a boom is created. Roads will be constructed to bring in the equipment, technicians and workers pour in, and on their heels come other people such as shopkeepers, who share the boom indirectly. Oklahoma City was a small town in 1900 with barely 9,000 inhabitants. With the finding of oil, it grew rapidly and has more than 500,000 people today.
In Venezuela, the city of Maracaibo was an unknown village at the beginning of this century, but is now the second largest urban centre of the country, with half a million people and all the modern amenities that ‘liquid gold’ can give. In recent years the city of Aberdeen in Scotland has undergone great changes and an influx of population because it has become the base for exploration and drilling in the North Sea.
In the past seepages at the surface gave a clue as to where oil might be found, or drilling was simply at random, but nowadays the search for oil is a much more complicated procedure, involving a wide knowledge of geology and geophysics. Before trial wells are drilled geologists study the surface rock outcrops from aerial photographs or in the field to determine the geological structure.
If this is suitable the area is subjected to further investigation to determine the arrangement of underlying strata. The geophysicists map the subterranean structure, using many sophisticated instruments. Soundings are taken by exploding dynamite at prospective drilling sites so that the vibrations can be recorded by seismographs.
Since different rock types are of varying density, the time taken for the shock waves to be reflected from the various layers gives valuable information about the depth and structure of the underlying rocks. The information is automatically recorded as a series of wavy lines, by sensitive instruments such as geophones, and the pattern is later interpreted by geologists.
Other instruments employed in the search for oil include the magnetometer which measures the variations of the earth’s magnetic field, and the gravimeter which measures the differences of the gravitational force of denser and lighter rocks. The presence of oil affects their readings and therefore gives an indication of where oil might be found.
Seismic methods of determining the geological structure are particularly important where the oil-bearing rocks lie under the sea- floor. In such cases little is previously known about the geological conditions, and soundings, made from ships which work systematically throughout a region, give a fairly complete picture of the submarine geology.
Before the introduction of geophysical instruments the chances of striking oil were very slight; only one well in twenty was likely to strike oil and billions of dollars were wasted in sinking ‘dry holes’. Today, however, waste is minimal and one drilling in three should strike oil.
Expenditure is very great because, apart from prospecting and drilling, finance is needed for research on petroleum conservation, and on finding more and more uses for oil, gas and petroleum byproducts. Demand for oil and gas as industrial and domestic fuels and for driving and lubricating motor cars and other machinery is so great, however, that the industry is very lucrative and the large companies can easily finance continual exploration in new areas, even where the difficulties are great as in the polar regions, e.g. Alaska, or the oceans.
The most familiar sights in the oilfields are the great steel towers or derricks, 35—60 metres (120— 200 ft) high, which mark the places where the oil is being drilled. In the past the derricks were made of wood but they are now made of steel and are portable, so that they can be taken down when the well is exhausted to be used again elsewhere.
In many parts of the world where oil occurs under the continental shelves, off-shore drilling has to be employed, e.g. in the Gulf of Mexico, the North Sea and off Malaysia, Brunei and Sumatra in the Sunda Shelf. Drilling is more complicated off shore as the derricks and other equipment have to be mounted on platforms.
These platforms may float or may rest on huge piles where the water is shallow. Many drilling platforms can be moved from place to place so that if drilling is unsuccessful the rig is towed to a new location. The platforms may be very near shore, but many are as much as 160 km (100 miles) out at sea and thus must be self-contained, with power plants, food and freshwater supplies, living quarters for the men, as well as boats and helicopters which ferry out men, equipment and food supplies.
There are two major methods of oil drilling: the percussion or cable-tool method and the rotary method. The former method was used by Edwin Drake and the earlier drillers for drilling shallow wells of not more than 610 metres (2,000 ft). It is cheap, but slow and inefficient and so is rarely used today. Modern oil companies use the more efficient rotary drilling method. Diesel engines move the rotary table and spin the kelly and the drill stem.
The drill stem carries steel drilling pipes each 9 metres (30 ft) long and 13 cm (5 inches) in diameter and at the bottom is the powerful drilling bit that cuts its way through the earth and rocks. As the drilling operation progresses, more and more lenghts of the steel pipe are added until the bore hole may be thousands of metres deep.
The bore hole is reinforced by steel pipes of larger diameter than the drilling pipes, which prevent it caving in. The crown block at the top of the derrick carries a pulley from which a travelling block is suspended by cables. Its function is to raise or lower the long string of drill pipes.
It is obvious that as more and more pipes are added to the drilling string, it becomes very much heavier. At a depth of 1,520 metres (5,000 ft), the string weighs as much as 50 tonnes. The rate of drilling varies from 76 metres (250 ft) an hour in soft ground to less than 0.3 metre (1 foot) an hour in harder beds.
Meanwhile, a lubricating ‘mud’ made from clay and chemicals, is pumped into the drilling pipes through the swivel and the kelly to the drilling bit. The mud then returns inside the casing which lines the hole. Besides cooling and lubricating the drilling bit, the mud also brings up rock fragments to be examined by geologists for oil. The vibrating mud-screen sieves the mud which is then stored in the mud pit for re-use. The cleansed mud is later passed back to the swivel to be pumped down the drilling string again.
Constant drilling will wear out the bit, which therefore needs regular replacement. Commercially used drilling bits are of three kinds. The fishtail bit, with a split-wedge shape like the tail of a fish, is used for drilling soft rocks like shale; the toothy rock drill which measures up to 0.3 metre (1 foot) in diameter and consists of a number of interlocking wheels, is very effective in cutting through hard rocks.
For hard drilling in very resistant rocks a special diamond- studded core bit is used. The industrial diamonds on the bit will cut through anything in the earth’s crust. They are widely used by geologists to obtain cylindrical core samples for rock analysis.
Another problem encountered in oil drilling is keeping the bore hole vertical and straight. The longer the drill pipe grows, the more flexible it becomes, and, unless great care is taken in checking the drilling line, it may never reach the intended position. Re-drilling is both costly and painstaking.
In some cases, however, it may be desirable to drill at an angle in order to reach an oil reserve not directly beneath the derrick. This is known as directional drilling. It is accomplished by varying the weight on the bit with the brake in the drawing works. Directional drilling is desirable when the oil sought lies below a lake, river, sea or even a group of buildings; or when it is desired to drill several wells from a single site.
When the drilling bit finally strikes oil- or gas-bearing rocks, gas and oil often gush upwards to the surface, because they are usually trapped under great pressure. The borehole releases the pressure and allows the oil to escape upwards. The final strike may be sudden and unexpected and carelessness may allow the escaping gas or oil to catch fire, with disastrous consequences.
The entire derrick may be destroyed and the fire, continually fed by oil and gas from below may last for a longtime and cause great damage, besides consuming the reserves of oil which had been tapped. The fire of Gassi Touil in the Sahara is said to have burnt up £10 million worth of gas before it was extinguished. Its 140 metre (450 ft) high flames could be seen by people more than a hundred kilometres away.
Not all oil wells are gushers. In some cases the pressure is low and oil has to be pumped to the surface from the outset. Most gushers, too, after the initial pressure release, cease to flow. After a time the oil or gas has to be pumped to the surface.
There are hundreds of thousands of oil wells in the world. The older ones are becoming exhausted or have already run dry, like those of the Appalachians, while many newer wells in Texas, the Middle East, North Africa, Europe, the U.S.S.R. and South-East Asia are still at peak production. The life and productivity of an oil well is difficult to predict accurately and so are the petroleum reserves.
The Spindle top oilfield at Beaumont, Texas, first drilled on 10 January 1901 yielded 100,000 barrels (13,500 tonnes) a day for the first 10 days and then declined gradually but flowed for many years. Some small wells last only a few days before being exhausted. Nowadays the expense of drilling and operating oil wells is such that wells are not brought into production unless forecast output and reserves are sufficient to offset costs.
Extraction becomes difficult when the pressure in the well becomes low but in some cases this difficulty can be overcome. Sea-water can be pumped into the well to replace extracted oil. The water sinks to the bottom of the reservoir rock forcing the oil to the top where it can more easily be reached.
Production in the southern Californian off-shore fields was boosted in this way. The flow of viscous heavy oil can be improved by pumping steam into the oil-bearing rocks. Production may be halted because the bore hole is clogged with heavy asphalt residues. It will then be necessary to send down strong acids to dissolve the clog or explode nitroglycerine in the borehole to provide new channels for the oil to reach the surface.
On average only about one-third of the oil contained in a rock can be extracted, either because the deposits lie too deep to be reached by available equipment or because, though they could theoretically be extracted, it would be uneconomic to do so. The continual improvement in oil mining techniques and equipment is enabling deeper and deeper reserves to be worked and is also allowing old areas, previously abandoned as unworkable, to be brought back into production.
Essay # 6. Transportation and Storage of Petroleum:
Petroleum is one of the few liquid commodities that is traded in large quantities and transported over long distances. It can be conveyed by road in oil trucks, by rail in tank waggons, by sea in oil tankers and even by aircraft for military and emergency purposes.
The bulk of the world’s crude oil from the oilfields is, however, transported by an endless network of pipelines, either to refineries or to the coastal shipping terminals. Pipelines are expensive to build, and once built, their route is fixed and cannot be easily changed. Before laying a pipeline therefore it is important for oil companies to be sure there will be a steady flow of oil through the line and a constant demand at the market end of the line.
If this is the case, pipelines are the most economical mode of transport for an inflammable liquid like oil. Where flexibility of routes is essential to serve varied or fluctuating markets, or where pipelines are often insecure for political reasons, tanker transport by sea may be preferred. The increase in tanker size so that large volumes of oil can be carried relatively cheaply has made tanker transport more economical in recent years.
The main trunk pipelines that cross deserts, forest and mountains are between 76 cm (30 inches) and 122 cm (48 inches) in diameter, or even larger, but the subsidiary lines are much smaller, between 15 and 61 cm (6 and 24 inches), with walls 0.6 cm (1/4 inch) thick. Numerous pumping stations are constructed along the pipeline to keep the oil flowing steadily at the rate of 5—8 km.p.h. (3—5 m.p.h.). On level ground the stations may be 240 km (150 miles) apart but on rugged terrain they have to be closer, about 48 to 80 km (30 to 50 miles), to maintain the flow.
There are many problems involved in laying, inspecting and maintaining the network of pipelines. The various lengths of the pipelines have first to be brought to the laying sites, where they are welded together, the joints being carefully sealed. The pipeline may lie on the surface in uninhabited areas but in densely populated or agricultural areas the line has to be buried so as not to interfere with other land use.
Very often several sets of pipelines run parallel to one another, belonging either to one corporation or to different oil companies. There are also pipelines from the refineries that carry different liquid products (petrol, diesel, kerosene or benzene) to the installations at consuming centres, e.g. products pipelines link the Fawley refinery in southern England with London. Natural gas is also carried by pipeline. Pipelines may be laid on the sea-floor to transport oil or gas from off-shore fields to refineries on land.
Precautions have to be taken to make sure that the pipelines are in perfect functioning condition. The steel pipes are coated with bitumen and wrapped in protective glass fibres before they are laid in the ground, to prevent corrosion. A perforated pipeline leaks and this can be very serious if the oil catches fire.
Large oil companies therefore maintain ‘beat walkers’ who patrol the pipe route to check any leakage and repair it on the spot. Trained dogs are also used for this purpose. In difficult terrain or in deserts, low-flying aeroplane patrols keep a watchful eye on the pipelines, reporting any leakage as evidenced by the discoloured ground.
In parts of Saudi Arabia and the United Arab Emirates local tribal leaders are paid well to guard the section of the pipeline which runs through their territory. Pipelines are easily damaged by saboteurs from unfriendly nations or by local anti-government groups and a watch is maintained to forestall such attack.
Some pipelines are fitted with automatic alarms that warn of any acute changes in pressure or leakages. Once any damage is reported, the preceding pumping station of the pipeline will be disconnected and the flow of oil halted while repairs are being made.
As pipelines thread through varied terrain, climbing hills and descending valleys, artificial pressure has to be applied to make the oil flow continuously. It flows easily downhill, but when ascending uplands the pumping station has to apply extra pressure to boost its uphill climb. For some heavy sluggish crude oils, it may be necessary to heat the oil before it can be made to flow easily.
The use of pipelines in oil transport first began in Pennsylvania, U.S.A., in 1861, when it was found that haulage in wooden barrels was far too expensive and inefficient. It began with wooden pipes covering only short distances, but later iron and steel pipes were developed. So much crude oil was produced in the various American oilfields that by the beginning of this century, the country was already criss-crossed by a network of pipelines, terminating in refineries and coastal ports.
Cylindrical storage tanks capable of holding over 800 tonnes of oil each became a common sight in many city suburbs. Pipelines carry oil the length and breadth of the country and even bring oil from Prudhoe Bay on the North Coast of Alaska to markets in mainland U.S.A. The demand for natural gas is also very great and pipelines distribute gas to such urban markets as New York, Boston, Chicago, Los Angeles and San Francisco.
The network of natural gas pipelines in the U.S.A. is now larger than that of the oil pipelines. Canadian pipelines are also very extensive, linking the oil and gas fields of Alberta with terminals at Sarnia on Lake Huron, the major population centres on the St. Lawrence and Great Lakes, and Vancouver on the Pacific coast.
There are very long gas and oil pipelines in the U.S.S.R. linking the trans-Urals fields with major industrial centres. There are also many important pipelines in the Middle East, the longest being the Tapline (i.e. Trans-Arabian Pipeline) which links the oilfields of the Persian Gulf with Saida (Sidon) in Lebanon on the Mediterranean.
The Tapline is 1,707 km (1,067 miles) long and was constructed in 1950 at a cost of £80 million by the Arabian American Oil Company (Aramoco). Its pipes are 76 cm (30 inches) in diameter and have a carrying capacity of more than 20 million tonnes a year. Other pipelines in the Middle East include the 896-km (560-mile) line from Kirkuk (Iraq) to Banias (Syria) on the Mediterranean coast.
Tankers are used to transport oil across the high seas and, since 1938, oil has taken first place amongst the cargoes carried by the world’s merchant fleets. The world’s petroleum resources are rather unevenly distributed. They are located chiefly in the U.S.A., Canada, Venezuela, the Middle East, the Sahara, and the U.S.S.R., with minor fields in Indonesia, Australia and Europe.
While U.S., Canadian, Russian and European production can be used locally many producing countries, especially in the Middle East and North Africa, have little demand for oil or its by-products. The oil, therefore, has to be brought to the industrial centres, such as Western Europe, the U.S.A. and Japan, where it is most urgently required. This necessitates the great international trade in oil.
Oil tankers are special cargo-ships built solely for the conveyance of oil. Pre-war tankers were small, between 12,000 and 30,000 tonnes, but the oil tankers today are much larger, carrying at least 50,000 tonnes of oil. Modern super-tankers may carry 300,000 tonnes of oil or more.
Each tanker is divided into thirty or more separate tanks to prevent the oil from surging and rolling about in the rough seas. The cargo can be easily loaded or discharged by pumping the oil through pipes. Where the sea is shallow near the coast as in Brunei or some parts of the Persian Gulf tankers are loaded by pipeline without ever reaching the shore.
Since the tankers carry such an inflammable liquid as oil, special devices have to be installed to fight any outbreak of fire. All the cargo compartments are lined with an intricate system of pipes, through which steam can be drawn in to smother the flames. In addition there are rows of fire extinguishers, fire hoses, water pumps and oxygen-breathing apparatus which can be readily made use of in the event of fire.
The greatest danger, however, often occurs when the tankers are empty and gases remaining in the tanks cause tremendous explosions, often sinking the tankers almost immediately.
Most of the world’s largest refineries are sited at ocean terminals where the tankers unload the crude oil. The oil is stored in huge tanks with storage capacities varying from 5,000 to 100,000 barrels (650 to 13,500 tonnes) each. They act as reservoirs, supplying the crude oil to the refining plants.
After refining, the various products, including petrol, diesel oil, kerosene and gases, are again stored in separate tanks before being distributed to consumers. Much of the oil is stored underground which is safe, economical and occupies least space.
Strict fire precautionary measures are taken in the tank farms. Each storage tank is provided with a gas- tight dip-hole and air-exit valves which counteract the differences in pressure when the tanks are heated by day and cooled by night. The roof is floatable to give room for ‘breathing’, caused by the expansion or contraction of the oil. The steel-plated tanks of 2.5 cm (1 inch) thickness are very durable.
They are coated with white or silvery aluminium paint to reflect as much as possible the direct rays of the sun and the roof is covered with insulating materials. Each tank is isolated from the others by a circular earth embankment. In the event of fire, this prevents the flames from spreading. At every convenient point is found fire-fighting equipment such as chemical and foam extinguishers, water hoses, and sand pits. In fact, every possible measure is taken in an oil installation to meet the eventuality of fire.
Transport from point to point within the tank farm is entirely by pipeline, and has all the advantages of push-button operation, economy of labour, economy of fuel, ease, and speed of bulk conveyance. Pipeline transport of oil products also links the major refineries with large consuming centres, e.g. London is linked by pipeline to coastal refineries. But after that, delivery of the refined products to consumers such as motorists, workshops and houses is dependent on the usual modes of inland transport: oil trucks, rail tank waggons or oil barges. These forms of transport, too, have to be specially constructed to give maximum safety from fire. They are usually loaded and unloaded by means of hoses.
An oil truck can carry as much as 18,200 litres (4,000 gallons) of petrol or 12.75 tonnes, though half that amount is usual with the smaller trucks. Rail tank waggons may have a capacity of between 14 and 35 tonnes. The oil barges in Netherlands and Germany can carry 500 tonnes of oil in oil drums.
Essay # 7. Reserves of Petroleum:
No one really knows how much petroleum is stored in the earth’s crust. Many estimates have been made in the past which have proved too small. In fact, exploration in all parts of the world is continually extending the known resources of oil, despite the fact that production and consumption continue to increase every year.
The world production of oil was 4 million tonnes in 1880, 20 million tonnes in 1900, 281 million tonnes in 1938, 1,057 million tonnes in 1960 and nearly 3,000 million tonnes by 1977. Proved reserves of oil, i.e., reserves whose existence has been proved by drilling, amount to over 74,500 million tonnes and the amount of oil still to be discovered in hitherto unexploited regions is probably much larger.
Taking only the proved reserves, however, there is sufficient supply of oil to last for about twenty-five years at present rates of consumption. The amount of known world reserves may be greatly increased by continued exploration and, at the same time, several factors may lead to a decreased rate of consumption.
The factors affecting the long-term future of the oil industry are outlined below:
i. Continued Exploration:
Many parts of the earth remain unexplored for oil, especially in remote areas where transport costs have been a deterrent. Much oil may also lie beneath the sea, but this, if found, would pose no problems of transport as.it could be easily moved by tanker or pipeline.
ii. Reserves at Depth:
Oil reserves may lie very deep in the earth’s crust, beyond the range of present equipment. Similarly, sea-bed reserves under a great depth of water are at present difficult to exploit but will certainly become available in the future as oil technology advances.
iii. Improved Drilling Techniques:
Better understanding of oil occurrence and exploitation enables oil men to recover a larger percentage of available reserves.
iv. Improved Refining Techniques:
Refining techniques have been greatly improved in the past enabling refiners to extract more of the most valuable fractions, such as petrol, from a given quantity of crude oil. Current improvements concentrate on making the best use of all the crude oil fractions, including gases, which were previously wasted.
Even impurities such as sulphur are collected for use in the chemicals industry. The next development will be the use of heavy asphaltic and waxy crudes, at present unusable by reason of their impurities. This trend will allow greater use to be made of known reserves and will reduce wastage.
v. New Oil Sources:
Developments in oil technology will undoubtedly make economic exploitation of oil shales and tar sands a possibility in future. When this happens the world’s resources will be greatly increased for such sediments are widely distributed and contain large reserves of oil.
vi. Fuel-Saving Transport Systems:
The rate of consumption of oil may be reduced by the development of better forms of transport which use less oil. For instance, automobile manufacturers have greatly improved the fuel-consumption characteristics of cars so that they can travel further on a given amount of petrol. The use of diesel rather than petrol is also economical.
The use of pipelines for the transportation of oil, gas and refined products requires less fuel than conventional forms of transport such as tankers, trucks or locomotives. In future pipelines will probably become much more common and may be used to transport other commodities than oil.
vii. Alternative Fuels:
There will undoubtedly be a great expansion in the use of fuels other than oil in the future. Natural gas, which was previously wasted, has already experienced a great rise in demand. The use of hydro-electricity, which relies on a renewable resource rather than a diminishing one, and the use of electricity generated by nuclear reactors, will also reduce oil consumption in thermal electricity generators, though this can only take place when nuclear power can be generated more economically than at present.
Most important, many automobile manufacturers are already developing alternatives to the internal combustion engine. When such alternatives can be made fully efficient and can be produced economically, the demand for petrol, and thus for crude oil, may be greatly reduced.
viii. Pollution Dangers:
It is already realized that carbon monoxide and sulphur in the exhaust fumes of motor vehicles are probably the major and most dangerous air pollutants. In almost every country of the world legislation is being enacted to reduce air pollution. This will undoubtedly lead to a speeding up of the development of alternatives to the petrol engine and also in the change to electric or geothemal energy sources, with a consequent reduction in the use of oil.
Despite these factors which, in theory should stave off a crisis in fuel supplies at least long enough for scientists and technologists to develop alternative energy sources, there are a number of worldwide trends which suggest that not only will action not be taken in time but that time is running out faster than we think.
Briefly these are as follows:
i. Expanding Consumption:
Oil consumption is still expanding and even steep rises in the price of oil during the 1970s have not halted this trend.
ii. Insufficient Research:
Money will not be forthcoming in sufficient quantities to develop alternative energy sources until a disaster makes it essential. Few world governments can afford to set aside large sums of money without being able to show a definite return on their investment.
iii. Opposition to Alternatives:
The chief present-day alternatives to oil in electricity generation are coal and nuclear power. Development of coal resources by economical stripping methods (in the U.S.A) and even underground developments (in Britain) is being delayed or rendered uneconomic by public pressure from environmentalists.
Nuclear power is also opposed by the environmental lobby on the score of the dangers associated both with the power stations themselves and with the disposal of waste products.
iv. Time-Lag in Changing To New Fuels:
No changeover in fuel consumption can be immediately effected either in industrial or domestic power supplies. Existing plants cannot be immediately converted or rebuilt to use another fuel. Thus a time-lag occurs between the recognition of the need for a new policy and the implementation of that policy.
v. Political Considerations:
The length of time that world reserves of oil will last depends on whether the countries which own them make them available to the countries that need them. The politics of oil supply and demand, especially in the Middle East, have become increasingly bitter and will probably cause more and more friction in the future.
Essay # 8. Uses of Petroleum:
Oil has a wide range of uses in industry, commerce, agriculture and other fields and has contributed greatly to world industrial development, especially in the last hundred years. It serves as a fuel, a lubricant, an illuminant and a raw material for a wide range of products. Its by-products are used in the chemical, pharmaceutical, textile and many other industries.
The major uses of petroleum in its many different forms may be described as follows:
i. Transportation:
The major use of petroleum is in transportation; almost half is used for motor fuel alone. The development of the internal combustion engine and of the automobile in the late nineteenth and early twentieth centuries created an enormous demand for the lighter grades of oil, and newer developments such as the jet engine have increased this field.
Petrol (gasoline) and diesel oil are used to drive cars, buses, lorries, motor cycles, small boats and a number of specialized vehicles, such as tanks and other military equipment; agricultural machinery such as tractors and harvesters; constructional plant such as diggers and bulldozers; and domestic equipment such as lawn-mowers. A range of aviation fuels is used by aircraft and jets, using special jet fuels, can fly at speeds faster than sound (335 m/s or 1,100 ft per second). Diesel and heavy fuel oils are used to power railway locomotives and steamships.
On almost all the world’s major railway networks, diesel trains have replaced the less efficient coal-powered steam trains. The boilers of steamships are also now almost universally oil- powered. Oil has many advantages for shipping because it is easily loaded, takes less storage space than coal and gives better results. Propane and butane may in future be more widely used to power vehicles as they cause less pollution.
ii. Industrial Power:
Oil is a major source of industrial power. Fuel oils (and natural gas) have largely replaced coal in the boilers and furnaces of factories. It is also very important in the generation of thermal electricity and is also used in the production of ‘town’ gas for domestic and industrial use. Lighter oils are used to power smaller plants, pumps and so on for industrial, agricultural and domestic purposes.
iii. Heating and Lighting:
Oil has many domestic uses. Heavier oils are used in central heating plants for shops and offices as well as homes, and of course oil contributes to the production of electricity for industrial and domestic use. The lighter grades of oil are also very important. Paraffin (kerosene) was one of the earliest oil products to be used widely.
It was used for lighting, heating and cooking, and though its use has declined in many advanced countries, where electricity and other domestic fuels are readily available, many people in less developed parts of the world or in the remoter parts of most countries depend on kerosene for light and heat. It is also used for light-buoys and signal lights, e.g. lighthouses, in many parts of the world.
Some of the petroleum-derived gases, especially propane and butane are also important domestic fuels. Sometimes called ‘calor gas’, these fuels are distributed in metal cylinders and used for lighting, cooking and heating in many areas. They are often cheaper and cleaner to use than kerosene.
iv. Lubricants:
Only 1 or 2 per cent of the crude oil distilled is processed into lubricants and greases but these nevertheless play an important role in transport and industry. Vehicles of all kinds and the vast range of sophisticated machinery in use in factories and offices today rely on lubricants, and would grind to a standstill if they were not available.
The largest machines require heavy greases, whereas smaller equipment such as typewriters, clocks and many domestic appliances require lighter oils. Motor vehicles require thorough and regular lubrication to run efficiently.
v. Petrochemicals:
Petroleum has become the raw material of an enormous range of chemicals industries, and in fact dominates the chemicals industry. By using such petroleum fractions as naphtha, ethylene and benzene, and performing a wide range of chemical reactions, many varied products can be made.
Amongst these are synthetic textiles, which account for a large share of the textiles industry as well as dyestuffs and other chemicals for the textile trades; fertilizers, insecticides and other chemicals for agricultural use; resins and adhesives for use in many industries; solvents and detergents; plastics which have a wide range of industrial and domestic uses in the form of plastic sheets, plastic foam, household goods such as bowls and buckets, upholstery and packing materials and so on; synthetic rubber which is used in the vehicle manufacturing industries and for many other purposes; paints and vinyl floor and furniture coverings used in house-building and decoration.
Carbon black, removed from the oil in the cracking process also has many uses such as making printing inks, paints, carbon paper, gramophone records and tyres. Sulphur and other chemicals are also produced for other branches of the chemicals industry.
The petroleum industry is thus an expanding industry, and as a provider of power, light and heat, as well as numerous chemical products, penetrates deep into every sphere of life, from the household to the largest industrial undertaking. It merits the name of the ‘modern industrial giant’.
vi. Other Uses:
The heavier residual substances such as asphalt, bitumen, pitch or tar are used for road-surfacing, roofing and water-proofing purposes, and petroleum wax is used for making candles, seals, polishes and illuminants. Vaseline is obtained from lubricating oils and benzole, a substitute for motor fuel, is obtained from residues. Certain of the refined gases and oils form the basis of pharmaceutical drugs.