Table of Contents
The Advantages of Obtaining and Using Each
Everything has its advantages and disadvantages. Petroleum oil and natural gas are not the exceptions. We pay great amount of money for their using, so a simple question appears in our heads - ‘why?’ It is because of its rareness and difficult, time consuming mining.
Natural gas is not a homogeneous substance. It consists of a mixture of various gases, which were formed in the entrails of the earth, by the decomposition of organic matters millions of years ago. Therefore, natural gas is in the earth at a depth from 1000 meters to several kilometers and could be obtained mostly by drilling. In the bowels, the gas is in microscopic cavities, called pores. The pores are interconnected by microscopic channels, which in turn are called cracks. By these channels, gas comes from the area with a high pressure, to the pores of a lower pressure. That is why, geological exploration must be held, in order to know where exactly the reservoirs of gas are. After exploration, wells are made. Wells are trying to place uniformly throughout the field. This is done to a uniform fall of pressure in the reservoir formation. Finally, the process of gas production begins.
As it was said before, natural gas is an exhaustive mineral, but there is no reason to worry, Bernard and Goldstein (2012) exemplify: “the Marcellus shale, a gas-bearing shale area in the northeastern United States, is believed to contain an energy content equivalent to three years of the current world use of oil. “ Therefore, abundant gas reserves still exist, and not only in the northeastern United States, but also near Ohio and all around the world. Moreover, another advantage appears – scientists and engineers never cease to amaze us with new technologies. So, new discovery was conducted in this area - hydraulic fracturing, also known as 'horizontal drilling'. This new technology now gives significant opportunity to obtain inaccessible natural gas and is used where conventional drilling is very expensive. Horizontal drilling covers a much larger contact area with natural gas than vertical wells. In addition, U.S. Department of Energy (2012) indicates : "that using horizontal drilling can lead to an increase in reserves in place by 2% of the original gas in place. The production ratio for horizontal wells versus vertical wells is 3.2 to 1, while the cost ratio of horizontal versus vertical wells is only 2 to 1." Decidedly, it is a good way out from the situation.
What is more, the gas may also be produced from decomposing biomass or recycling of waste, but it is a small amount. Meanwhile, natural gas influences our life very much. On the one hand, this mineral is a universal fossil fuel, which is used for heating, electricity production, cooking, transportation and for many other purposes. Moreover, one-quarter of the U.S. energy is made up by the gas. But, on the other hand: “successful release of water and chemicals deep underground” (Bernard, 2012) perniciously hits our environment. This safety issues generate heated discussion. However, Union of Concerned Scientist (UCS, 2010) came to the following results:
Despite significant environmental concerns associated with its extraction and production, natural gas burns more cleanly than coal and oil and therefore offers a substantial advantage in reducing global warming emissions and improving public health. Natural gas is an appealing option to serve as a near-term ‘bridge’ as we transition toward a sustainable energy economy, but we must work to minimize the environmental impacts of its production and use.
In contrast to UCS, Economides (2012) remembers “uncertainty supply and substantial price volatility” in the recent past years. His attention also is attracted by a great number of disadvantages caused by the impact of natural gas, for instance: air, water, soil, noise pollution, worker health and safety, community safety; traffic, explosions, fires, crimes; global climate changes or lack of sustainability.
Also transporting of the gas should be mentioned, as it is not a simple process. Currently, the main mode of gas transporting is the pipeline. The gas, which is under pressure, moves through the pipes and loses energy to overcome frictional forces between a gas and pipe wall, and between the layers of the gas. Therefore, at fixed intervals compressor stations (CS) with the compressor units must be constructed, where the gas pressure reaches the design pressure. Construction and maintenance of the pipeline are rather expensive, but it is the cheapest way to transport not only natural gas, but also petroleum oil. The total length of pipelines in the U.S. is 79.3 thousand km (as of 2006). Despite pipelines, also special tankers are used, which are called - gas carriers. These special ships transport the gas, which is in a compressed or liquefied state at certain thermobaric conditions. For transportation of the gas in this way, it is required : to extend the pipeline to the sea, build on the shore of sea a gas factory, that changes its state, port for tankers and tankers themselves. All these seem to be over expensive, but actually under favorable conditions, the price on supplies, by tankers may be lower, than by pipeline nearly doubled - it is an economy of maritime transport, but nevertheless transportation by pipeline is used much more often.
Gas production is increased every year and in 2001 - amounted to 2,493 billion cubic meters, while in 2011 became - 3,193 billion cubic meters, so natural gas is widely recognized and consumed almost by all people throughout the world, while its value is hard not to overestimate.
Petroleum oil is a fossil fuels. This mineral is a thick, oily liquid of dark color, which lies at great depths in the bowels of the earth. Petroleum consists of a mixture of chemical components, of particular hydrogen and carbon. Combustion of hydrocarbon emits heat, that is why the oil is used as raw material for production of fuel. Heat of evaporation of petroleum distillates at atmospheric pressure is 160-320 kJ / kg. The heat of combustion of oils ranges from 40 to 45 MJ / kg, and it is greater, the smaller the density of oil or fractions. It is a great advantage, as emission of the heat creates powerful energy, which is used in everyday life.
Plants and animals, which lived in ancient seas millions of years ago, after the death settled to the bottom, decomposed into the silt and stood long. Gradually the mud transformed into a solid rock, which in turn under the action of heat coming from the bowels of the Earth over millions of years, transformed into the oil. As a consequence petroleum, as well as, natural gas is found in the entrails of the earth, and in order to extract the oil, a well must be drilled. There are three general methods of using oil wells: oil ‘gusher’, oil ‘compressor’ and oil ‘pump’.
Oil 'gusher' is the cheapest, easiest and the most productive method. Therefore, more than half of the world oil production is obtained exactly by this way. Extraction occurs, when formation pressure exceeds the pressure in the well. This difference of pressure plays a leading role in using oil wells. However, when difference of pressure is insufficient for using oil ‘gusher’, petroleum is obtained by compressors and pumps. Compressed to 40-50 atm. petroleum gas or air is incited through pipes (elevators) which, by mixing with the oil, reduce its weight. Consequently, second method - oil ‘compressor’, is also built on the use of pressure. This method is mainly used for oil with high content of sand and operation of distorted wells. Meanwhile, when the previous two methods are not possible to use, oil ‘pump’ method takes the advantage. This method, in general, is based on pumping system. Steel-rocking machine pumps from the reservoir in average 10 tons of oil per day and by the number of wells this method is the most common. Almost all oil production is accompanied by removal from the natural underground reservoirs significant quantities of gas, water, mechanical impurities and salts.
At first sight, extraction of petroleum is not complicated thing, that is why attention should be paid on the fact that only crude oil is obtained. Crude oil is not straightly used. In order to receive its technically valuable products, mainly gasoline, motor oil, raw materials for the chemical industry, it should be remade. All refining processes, which are associated with heating or cooling, require a comprehensive study of thermal properties of petroleum and petroleum products, it is laborious and expensive process and this disadvantage cannot be hidden as it directly influences the price of oil and all products.
Refinery is a giant factory, which makes desalting, dehydration and stabilization of crude oil. One of such refinery is the Chevron refinery. This refinery, which is located in California, was built more than 50 years ago and is the largest in Northern California and the third largest in the country. Chevron is able to process over 240,000 barrels of oil per day and it is an eighth part of the processed oil in the U.S.. Over the years, Chevron plans an overhaul and modernization of the company. However, local residents voted "against", considering that the reconstruction of refineries will cause great damage to the ecology of the city. Unfortunately, lately an accident happened. Refinery caught fire and a pillar of black smoke rose to tens of meters up. It is another disadvantage and a smashing example of risk and costs, which refining has.
Oil products, which people use in everyday life, were in all spheres of life. Petrol and diesel for cars, jet fuel and fuel for vehicles, tar for asphalt obtaining, paraffin and Vaseline, motor oil and many other products are benefits of petroleum oil. As explained by Roberts’s and Wilson’s (2011) researches: “The world guzzles this highly concentrated fossil fuel at a rate of nearly one thousand barrels per second (29.2 billion barrels in 2009, according to the BP Statistical Review of World Energy 2010). The U.S., with 4.5% of the world's population, consumes 22.2% of its petroleum. A lot of that (71%) is for transportation; 97% of our vehicles are powered by petroleum fuels. Our minds are alerted by these figures, with a question: 'Are we running out of oil?' Definitely, the answer is ‘no’. “There is still a great deal of oil that can be extracted, and mammoth new discoveries deep under the Gulf of Mexico and off the coast of Brazil are adding to known reserves"(Roberts, 2011).
Of course, great deals of disadvantages exist. Oil combustion heavily pollutes the environment and badly impact on people's safety, as accidents happen, when petroleum is obtained, transported (particularly accidents at sea) or being remade at factories. Despite that, oil production is an engine of the economy development, it also could cause worldwide crisis. This can happen when oil prices rapidly increase. Krugman (2008) affirms: “I expect that prices will increase further in future – possibly far more, than anyone is now expecting and just hope that Faber was wrong about this. And, in the case that oil prices were to rise in real terms to their 1980s highs – well over US$ 100 – then the foundation for World War Three would be laid …” What is more in 1973 world oil production exceeded 2.8 billion tons, while in 2005 was 3.6 billion tons. This growth is natural as society develops and new sources of energy are needed.
That is why, alternative fuels should be searched for, in order not to be dependent only on petroleum. During the energy crisis of the 1970s alternative energy sources, which could replace oil, have been sought, for instance: in Canada oil sands (where after the disappearance of light fractions are heavy oil, bitumen and asphalt ) were developed, in U.S. large reserves of oil shale were discovered. Therefore, as we can see there is always an exit from the situation.
With no doubts, a lot could be said about petroleum oil and natural gas. They are as similar as different. The gas and oil have their own benefits, but also badly damage our environment. In comparison natural gas is quite clean-burning fuel and it does not harm the environment to such extent as petroleum does. Although the gas is not an ideal energy source, it is not so powerful as oil is while also we should not forget about nuclear energy, but that is another story.
It was mentioned rightly - everything has its advantages and disadvantages. Nevertheless, all in all, these two the most influential mineral always are under attentive supervision of the public eye and will astonish us repeatedly.