Eszterházy Károly College Faculty of Natural Sciences
Petroleum is still the main energy source that matters, not only economic but also political issues are dependent on it. Industrial scale using began approximately100 years ago. The initial oil reserves were estimated at around 300 million tonnes, the global production is approximately 3 million tons / year. Estimates of the remaining available resources vary, but we can say that the amount of time that the oil reserves are sufficient can only be measured in decades. (Figure 3). Gasoline and diesel produced from petroleum are the most widely used fuels. Its success is due to competitive extraction, transportation due to the physical state and distribution next to its superior physical and chemical properties. The use of petroleum products is indispensable in our everyday life. The use of petroleum is complex, it is used as fuel to produce electricity, and also fornindustrial and transportation purposes. The transport sector is the most dependent on petroleum. Petroleum demand is growing every year and this can only be met by increasing production. The use of petrol and diesel derivatives have serious environmental implications. Beside the carbon dioxide released from burning petroleum the risks associated with the extraction and transport have to be considered as well. In case of an incidental disaster we will have to resign from the stocks but also serious environmental problems will be caused, like the accident of the oil rig of the British Petrol in 20.04.2010 in the Gulf of Mexico.
Figure 3. Production and Consumption of Petroleum (own work) Source: BP Statistical Review of World Energy, 2012.
The composition and quality of petroleum derivatives are depending on the applied technology and the composition of petroleum. The main components are generally hydrocarbons: paraffins, olefins, cycloparaffins and aromatic compounds: phenols, carboxylic acids, carboxylic acid esters, sulfur-and nitrogen-containing compounds. The first step is purification, in which excavated dirt, water and natural gas are removed from petroleum. The second step of distillation. In this process different components will be allocated at different boiling points: gasoline 40-200 ˚ C, gas oil 200-350 ˚ C, above 350 ˚ C the lubricating oil. As the remainder of distillation bitumen and asphalt are produced.
The demand for natural gas grew faster than the demand for petroleum or coal. The demand will continue to rise as it is widely available. Its extraction is beneficial economically and environmentally than other fossil fuels. The reason is that per unit of energy output can be extracted with minimum amount of carbon dioxide emission, although it is environmental polluting. It should be noted that natural gas contains significant quantities of methane, which is an extremely harmful greenhouse gas. Methane has 23 times greater global warming effect than carbon dioxide, so that above all should be considered. The gas supply is technologically more complex and costly than petroleum because the transportation of petroleum is more diversified. The transportation of natural gas is only feasible economically with lines, since during transportion by tanker containers natural gas should be liquefied, which requires a very expensive infrastructure. Natural gas has lower energy density than petroleum, so transport purposes are only possible in large pressure-resistant container. The life expectancy of natural gas reserves are about 150-200 years, taking the current production into account. However, the life expectancy of economically recoverable reserves are much smaller. Calculating with the consumption rate of 2011 reserves are only sufficient for 64 years. The fact that over the past 30 years natural gas reserves increased three-fold since its been discovered in many parts of the world and new technology methods have made it possible to increase the existing reserves gives reason for optimism. (Figure 4).
Natural gas plays a major role in the energy supply of Hungary, providing a significant portion of our energy use. We use it to produce electricity and heat. The difference between the declining domestic production and the rising consumption is covered by imports. Hungary has wired connections through Russia and Austria which deliver according to contracts.
To the formation and accumulation of petroleum and gas the following basic conditions are required:
Mature source rock. It is usually dark gray to black, fine-grained, rich in organic clay, shale and carbonate rock. The "maturity" means that the rock was subjected to high temperature conditions (> 60 ° C) in the geological past so transformation of the organic material could happened.
Good reservoir rocks. Basic characteristics of the reservoir rocks are significant porosity and permeability. This may be sandstone, limestone cracks, or any other fractured rock.
Migration is possible between the source rock and reservoir rocks.
Non-permeable cap rock layers above the reservoir rocks.
Formation of trap. The source rock, reservoir rocks and cap rocks form a structure in which petroleum and natural gas can not elmigrate.