Oil and gas, in similar manner to coal, are generally the result of the degradation of organic materials, primarily plankton, which settled on the seafloor millions of years ago. This process occurred in the so-called "source rock", where the biomass was trapped along with other sediments. Depending on the depth at which this source rock was buried during its existence, the biomass will form either oil or gas. If this source rock was buried for a sufficient time between 2500 and 5000 m depth, where the temperature is around 80 °C, the hydrocarbon chains will break to form mainly oil. At depths exceeding 5000 m, however, usually no oil will be found, and at temperatures around 145 °C at that depth, over the geologic time, all carbon-carbon bonds will break to form the dominant component of natural gas: methane. The formations from which oil and gas are extracted are generally different from the source rock in which they were originally formed, however. In fact hydrocarbons, once liberated from the source rock, can migrate upward to form shallow oil or gas fields called "reservoirs", or even appear as surface oil seeps, for example as in the Los Angeles Basin at the La Brea Tar Pits in Southern California.
Natural seepage of oil has been used since ancient times in locations in the Middle East and the Americas for a variety of medicinal, lighting, and other purposes. Petroleum was referred to as early as the Old Testament. The word petroleum means "rock oil" from the Greek petros (rock) and eiaion (oil). Uses of petroleum oil, however, were very limited and it was not before the mid-19th century that wide use and the real potential of these natural resources began to evolve.
America's first commercial oil well was drilled in 1859 by Colonel (titular) Edwin Drake near Titusville in the State of Pennsylvania (Fig. 3.1), yielding about 10 barrels of oil per day . Drake's single well soon surpassed the entire production of Romania, which was at that time a major source of oil for Europe . The area was known previously to contain petroleum, which seeped from the ground and was skimmed from a local creeks surface called therefore "Oil Creek". Drake was a former railway conductor who, because of ill health, was urged by his doctor to move from the east coast to a more rural area. The "Colonel" label was given to him not as a result of any military service but by the Seneca Oil Company, which hired him and believed that such a title would help Drake to get the assistance of the local people. The efforts to find oil grew out of technology evolution and the need for lubrication and illumination products. Without evolving markets and processes for such products, Drake would have never been sent to the Pennsylvania hinterland to prospect and develop his oil operation.
In the mid-19th century, the need for illumination in cities such as Boston or New York led to the development of gas lighting. This was not done using natural gas, but by employing an illuminating gas that was produced by heating coal at gasworks located at the edge of the towns. Where gas was not available, and before the discovery of oil, whale oil more than any other product was used to fulfill the demand for clean and efficient illumination. Operating out of the North-Eastern United States, and later Hawaii and the North-Western States, the American whaling fleet mainly searched for sperm whales which contained large amounts of high-quality oil. However, with a steadily declining whale population, coupled with supply problems during the civil war, and ever-higher prices, the need for less expensive or more easily available alternatives was growing. The advent of petroleum oil signaled the end of the use of whale oil, these lamp oils were replaced by the more convenient and easily obtained, and seemingly inexhaustible, kerosene.
Kerosene, which was derived initially from bituminous coal and also known as "coal oil", proved to be a competitive illuminant during the 1850s, although its
foul odor kept the rate of development relatively slow. The name kerosene was quickly extended to all illuminating oils made from minerals, however. For the production of kerosene, petroleum oil could be used instead of coal in the same distillation process, and the product was distributed over the same existing network, thereby facilitating its development as a fuel. On a positive point, these fossil fuel light sources put an end to sperm whaling for oil, just as the use of coal had helped to save the remaining forests.
Kerosene was the first petroleum product to find a wide market, allowing John D. Rockefeller Sr., a Cleveland (Ohio) entrepreneur, to build his Standard Oil Company into a vast industrial empire that would, during the subsequent rise in the use of gasoline and the internal combustion engine, enjoy a virtual monopoly over the production and distribution of oil in the United States. In 1911 however, Standard Oil, due to antitrust regulations, was broken up into a number of separate companies, including those which became Chevron, Amoco, Conoco, Sohio and, of course, Mobil and Exxon. The later two giants recently merged again without causing much public concern. "Tempora mutantur" - such is the effect of changing times.
The discovery and uses for petroleum has paralleled and, to a large extent been responsible for, the growth in oil production. Inspired by the invention of the gasoline-burning engine by Nikolaus Otto in 1876, the combination of Gottlieb Daimler's engine, Carl Benz's electrical ignition and Wilhelm Maybach's float-feed carburetor resulted in the 1890s in the first successful commercially produced internal combustion automobile (Fig. 3.2). Henry Ford's mass production methods soon made it widely available and changed mankind's life in the 20th century (Fig. 3.3).
The use of oil began to increase dramatically to produce the large quantities of gasoline needed to fuel automobiles. However, the amount of gasoline that could be obtained from crude oil was low, anywhere from 10 to 20%. The original production process was based on simple distillation (fractionation), separating hydrocarbons through differences in their boiling points. Later, due mainly to growing demand, the refining of crude oil to yield a range of liquid fuels suited to a variety
of specific applications that ranged (eventually) from massive diesel locomotives to supersonic airplanes, was transformed by the introduction of cracking and other refining processes. Thermal cracking in combination with high pressure was introduced in 1913. The high temperature and pressure reproduced, on a short time scale, the naturally occurring process in breaking larger molecules into smaller ones. This process was further improved by the introduction of catalytic cracking in 1936. World War II saw also the introduction of high-octane gasoline produced by alkylation and isomerization. Without these processes it would be impossible to produce, inexpensively, the required large amounts of more valuable lighter fractions from the intermediate and heavy, higher molecular weight compounds of the crude oils. Furthermore, with these processes, the route to petrochemicals was opened up, since cracking provides the ability to produce unsa-turated hydrocarbons - molecules which, in contrast to saturated hydrocarbons (paraffins), the main components of oil, can be readily used and further transformed in chemical reactions to yield products such as lubricants, detergents, solvents, waxes, pharmaceuticals, insecticides, herbicides, synthetic fibers for clothing, plastics, fertilizers, and much more. Today, our daily lives would be unthinkable without all these products.
Since the first "black gold" rush initiated by Drake in Pennsylvania, the search for new oil fields worldwide has never stopped. The most intensive exploration occurred in the United States, where vast quantities of oil were found in a number of States including Oklahoma, California, Texas and, more recently, Alaska. In Eurasia, the earliest oil exploitations occurred around the Black Sea and on the Caspian Sea near Baku in the then Russian Empire (now Azerbaijan), where the Swedish Nobel family had for some years held the concession for oil production. More recently, in the harsh regions of Siberia, vast reserves of oil were found and developed. In Sumatra, Java and Borneo, petroleum resources have been exploited since the second half of the 19 century.
In the Middle East, exploration for oil began during the 1910s, and this led to the discoveries of the world's largest oilfields; al-Burgan in Kuwait, the world's second largest oilfield in 1938 and Saudi's al-Ghawar, the world's largest super-giant oilfield containing almost 7% of the world's oil reserves (according to estimates in 2000), a decade later. Other major oil production areas include South America, South-East Asia, Africa and, more recently, the North Sea.
Oil extraction begins with the drilling of a well. Edwin Drake's first oil well was only around 20 m deep. With rotary drilling techniques, used for the first time at the Spindeltop well in Beaumont, Texas in 1901, oil wells surpassed 3000 m in the 1930s, and drilling production wells deeper than 5000 m are now possible and used in several hydrocarbon reservoirs. A relatively recent innovation in drilling technology has been the routine use of directional and horizontal drilling. For the same reservoir, horizontal wells can produce several times as much oil as a traditional vertical wells. The longest horizontal wells are now around 4000 m in length.
In the early days of oil exploration, drilling took place exclusively on land, but moved to off-shore locations as the land deposits became less abundant and the necessary technologies were developed. The first off-shore well was drilled at Summerland, south east of Santa Barbara, California in 1897, and the first deep-water off-shore oil well along the Gulf coast of Louisiana in 1947. Today, some of these off-shore platforms are working in waters 2000 m deep or more.
Since oil reservoirs are unevenly distributed and often far away from major consumption centers, the crude oil must be transported over long distances, sometimes thousands of miles. For the long-distance transport of oil products on land, pipelines and railway tank cars are used. Pipelines are expensive to build and maintain, and breaks along the line can cause severe oil spills. However, they are the most energy-efficient means of transporting oil overland.
When oil must be transported overseas, for example from the Persian Gulf to North America or Europe, it is carried in specialized oil tankers. The need to carry ever-increasing quantities of oil has resulted, since the 1970s, in the construction of so-called "supertankers"; these are the largest ships afloat in the world, and larger even than aircraft carriers (Fig. 3.4). However, if a tanker is damaged in an accident it can cause severe environmental problems. Some of the oil spills resulting from such accidents have become very famous (or "infamous"). For example, the Amoco Cadiz, which in 1978 broke up off the coast of France spilling 1.6 million barrels of crude oil damaged not only the ecosystem but also the lucrative French tourist industry. In 1989, the Exxon Vaidez spilled almost 270000 barrels off the coast of Alaska. Despite the increasing oil quantities transported overseas, the amount of oil spilled has decreased over the years, thanks to the development of new technologies and infrastructures such as double-hulled tankers or deep-water "superports".
The 20th century saw a tremendous increase in the use of oil for a variety of purposes. With the development of the automobile and diesel locomotives, oil replaced coal as the main fuel for transportation. Oil also replaced coal as the primary home heating fuel because of its greater convenience. By the mid-20th century oil had become the world's primary energy source, but after the two oil crises of the 1970s and concerns about the reliability of our oil sources, another fossil fuel was gaining wider use, namely natural gas.
Natural gas used to be regarded as an undesirable byproduct of petroleum production, and was simply burned, or "flared" at the oil wells. This is still done in some parts of the Middle East or some off-shore platforms around the world, where no nearby markets exist for natural gas and transportation to more distant markets is not yet economically feasible. Most commercially sold natural gas comes from wells, which are used solely for natural gas production.
Before the nature of natural gas was understood, it posed a mystery to mankind. Sometimes, lightning strikes would ignite natural gas that was escaping from the Earth's crust; this would create a fire coming from the Earth, burning the natural gas as it seeped out from underground. These fires puzzled most early civilizations, and were the root of much myth and superstition. One of the most famous of these flames was found in ancient Greece, on Mount Parnassus, approximately around 1000 bc. According to the legend, a goat herdsman came across what looked like a "burning spring", a flame rising from a fissure in the rock. The Greeks, believing it to be of divine origin, built a temple over the flame. This temple housed a priestess, who was known as the Oracle of Delphi, giving out prophecies she claimed were inspired by the flame.
Such flames became prominent in the religions of India, Greece, and Persia. Since the origin of these fires could not be explained, they were often regarded as divine, or supernatural. It was not until about 500 bc that the Chinese discovered the potential to use such fires to their advantage. After first finding places where gas was seeping to the surface, the Chinese built crude pipelines from bamboo stems to transport the gas, which was then used to boil sea water, separating the salt and making the water potable.
In America, naturally occurring gas was identified as early as 1626, when French explorers discovered natives igniting gases that were seeping from the ground around Lake Erie. Indeed, the beginnings of the American natural gas industry arose in this area. Actually, the very same first well dug by Colonel Drake in 1859 was producing not only oil but also natural gas. At the time, a 5-cm (2-inch) diameter pipeline was built, running some 9 km from the well to the village of Titusville, Pennsylvania. The construction of this pipeline proved that natural gas could be brought safely and relatively easily from its underground source to be used for practical purposes. For this reason, most consider this well as the beginning not only of the oil industry but also of the natural gas industry in America.
In 1821, the first well specifically intended to obtain natural gas was dug in Fre-donia, New York, by William Hart. After noticing gas bubbles rising to the surface of a creek, Hart dug a well about 10 m deep to obtain a larger flow of gas to the surface. Hart is regarded by many as the "father of natural gas" in America. Expanding on Hart s work, the Fredonia Gas Light Company was eventually formed, becoming the first American natural gas company.
In 1885, Robert Bunsen invented what became known as the Bunsen burner (Fig. 3.5). He created a device that mixed natural gas with air in the correct proportions, creating a blue flame that could be safely used for cooking and heating. The invention of the Bunsen burner opened up new opportunities for the use of natural gas. The invention of temperature-regulating thermostatic devices made it possible to better use the heating potential of natural gas, allowing the temperature of the flame to be adjusted and monitored.
Without any means of transporting it effectively, natural gas discovered prior to World War II was usually just allowed to vent into the atmosphere, or burned when found together with coal and oil, or simply left in the ground. Transportation by pipelines developed only gradually. One of the first natural gas pipelines of considerable length was constructed in 1891; this was 200 km long, and carried natural gas from wells in central Indiana to the booming metropolis of Chicago. This early pipeline was very rudimentary and used no artificial compression, relying completely on the natural underground pressure. As might be imagined, the pipeline was not very efficient in transporting natural gas. It was not until the 1920s that any significant effort was put into building a suitable pipeline infrastructure. However, it was after World War II that newly developed welding techniques, pipe rolling, and metallurgical advances permitted the construction of reliable pipelines. The post-war pipeline construction boom lasted well into the 1960s, and allowed many thousands of kilometers of pipeline to be constructed in America and worldwide.
Once its transportation was made feasible and safe, many uses for natural gas were developed. These included its use to heat homes and operate appliances such as water heaters, cooking oven ranges, and clothes dryers. This was made
relatively easy because customers were already comfortable with the town gas which was generated from coal and had been widely used for close to a century.
Industry also began to use natural gas extensively in manufacturing and processing plants. Natural gas was also increasingly used to generate electricity. Its transportation infrastructure had made natural gas easy to obtain, and it became increasingly a most popular and efficient form of energy.
Moving large amounts of natural gas by pipeline is relatively easy, but the process is not adaptable to transport natural gas from remote locations far from consumer markets such as Saudi Arabia to North America or Europe. Because of the gaseous state of natural gas, it occupies enormous volumes compared to liquid or solid fuels. For intercontinental transport, across oceans, natural gas is usually liquefied to yield liquefied natural gas (LNG). This process is, however, energy-intensive, and requires specially designed and highly expensive tankers that keep natural gas at or below its boiling point (-162 °C) in highly insulated, doublewalled tanks. LNG can also be dangerous. In 1944, the explosion of an LNG storage plant in Cleveland, Ohio, killed 128 persons and injured several hundreds. More recently, in 2003, 27 people were killed in the explosion of a natural gas liquefaction plant in Algeria . A study by Sandia National Laboratory found that an explosion from a LNG tanker leak could result in major injuries and signifi cant damage up to 500 m away from the leak, while people up to 2 km away would suffer second-degree burns . Besides accidents, LNG facilities and tankers are also potential targets for terrorists. For these reasons, LNG terminals are usually not welcomed near major cities or population centers and are increasingly located off-shore.
Today, natural gas is extensively used because of its clean-burning properties and convenience, for space heating and generation of electricity to replace older and more polluting coal-fired power-plants. From an environmental point of view, natural gas is also advantageous because it produces the least amount of CO2 greenhouse gas per unit of energy generated.
As the 19th century had been the golden age of coal, the 20th century saw the rise of petroleum oil and natural gas as the new "kings" of fuels. Advances in the petrochemical industry, which provide us with many of the necessities of modern life, may be credited, more than anything else for the high standard of living that we enjoy today. As we advance into the 21st century, the use of oil and natural gas will continue. The unquestionable fact, however, is that these non-renewable resources are limited. With their increasing use and the growing population of the Earth, they will become increasingly scarce and expensive. We have no choice but to develop new sources and technologies in order eventually to replace fossil fuels. The time to do this is now, when we still have extensive sources of fossil fuels available to make the inevitable changes gradually, without major disruptions or crises.
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