Hydrocarbons: a Fossil but Not (Yet) Extinct Image Courtesy of the Shell Library
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sis_12_RZ:Layout 1 31.07.2009 12:31 Uhr Seite 62 Hydrocarbons: a fossil but not (yet) extinct Image courtesy of the Shell Library Continuing our energy series, Menno van Dijk introduces us to the past, present and future of hydrocarbons – still the most common of all fuels. hile researchers today are isms. They all extracted the energy for Wworking on the development their organic molecules either directly of clean, renewable fuels, our society or indirectly from sunlight. is still almost entirely dependent on fossil fuels. How are they formed, Storage in reservoirs how much is there of them, and how Since then, the continents have long will they last? drifted apart, with some landmasses Hundreds of millions of years ago, disappearing into the depths and oth- the world was a wilderness, but not ers being heaved up. Wind, ice and void. A diversity of animals and rain caused erosion on land, which plants populated the landmass. The created great masses of sediment, seas bubbled with life and, like today, especially in river estuaries. Some the largest part of the biomass con- sediments were porous (such as sand sisted of microscopically small organ- or the skeletons of calcareous ani- mals), others impermeable (such as ly of carbon (C) and hydrogen (H), clay). Organic material was buried, they are collectively called ‘hydrocar- too, and the vertical movements of bons’. This fluid, mostly together with landmasses could take it several kilo- water that was also trapped, worked metres below the ground. There, it its way up through porous rock until was warmed up by heat from the it was – in some cases – stopped by interior of Earth. an impermeable layer of sediments. The high temperature and high Where the geometry, determined by pressure at that depth caused the breaks and deformations, had formed organic material to break down and three-dimensional enclosures, or be converted to a fluid with a diverse reservoirs, the fluid accumulated and collection of chemical structures: remained there to simmer quietly. volatile hydrocarbons such as Due to the absence of oxygen, the Detailed image of a carpet moss leaf methane and ethane, short and long solar energy stored as chemical ener- (Mnium hornum); the parts of the plant paraffinic molecules, aromatics, and gy in the molecules was not burned cells which store light energy as molecu- highly complex and large polycyclic up (oxygenated), but preserved for Image courtesy of Kristian Peters and Hans Ferdinand Maßmann; image source: Wikimedia Commons Wikimedia Maßmann; image source: and Hans Ferdinand Image courtesy of Kristian Peters lar fuel (chloroplasts) are clearly visible. structures. Since they all consist main- millions of years. Sometimes a sepa- 62 Science in School Issue 12 : Summer 2009 www.scienceinschool.org sis_12_RZ:Layout 1 31.07.2009 12:31 Uhr Seite 63 Science topics The Brent Alpha platform in the North Sea Image courtesy of Mayumi Terao / iStockphoto ‘gas bubble’ formed. Note that such a its own character in terms of reservoir gas bubble, just as an oil reservoir, is shape and hydrocarbon composition. enclosed in porous rock, the pores of which are filled with oil and/or gas Energy hunger in the and/or water. modern world On land, organic material such as Over time, we humans have devel- trees and plants got buried, too. oped a great hunger for energy. Under favourable conditions, when Originally, this was fulfilled by fire- they were quickly covered by sedi- wood. When the growing of wood ment and thus sheltered from oxygen, couldn’t keep up with the growing preventing rot, these were converted demand for energy, we started dig- An offshore drilling rig to thick layers of coal. In some places, ging up million-year-old firewood the hydrocarbons came into contact from coal mines. But the solid form of rate gas phase was formed above the with bacteria with an appetite for cer- coal was cumbersome, dangerous to oil, and on other occasions, when tain molecules, which changed their dig up and not very economical. only very small hydrocarbon mole- composition. So each reservoir storing Eventually, oil reservoirs were discov- cules found their way to a reservoir, a accumulated solar energy will have ered. While man’s use of oil dates to www.scienceinschool.org Science in School Issue 12 : Summer 2009 63 sis_12_RZ:Layout 1 31.07.2009 12:31 Uhr Seite 64 Image courtesy of Jupiterimages Corporation prehistory, the first modern oil well much as the first source in Miri pro- was drilled in the United States on 27 duced in 60 years: that’s 650 000 bar- August 1859 by Edwin Drake in rels of oil, about 100 000 m3. Pennsylvania. Later, wells were drilled especially in the Middle East, Where to go from here? where vast resources of fairly easily One thing is clear: all the oil or gas extractable oil appeared to be situated that has been pumped out is gone for- under the sand. ever. Slochteren is running out, the The combustion engine caused an famous North Sea fields are running explosive growth in the demand for out, and even in the Gulf of Mexico, oil. This grew so quickly that the end the most important oil source for the of the supply seemed near. The Club most energy-hungry country in the of Rome, a global think tank for polit- world – the USA – the fields being ical issues, warned that mankind was found are increasingly small. Will the quickly running out of energy hydrocarbon economy soon die a reserves. So people started to search slow, or perhaps a quick, death? in more inaccessible places and dis- Ultimately, supplies are certainly covered much more oil under water: finite, but there are still a few aces up the North Sea, the Gulf of Mexico, the the hydrocarbon sleeve. Niger Delta in Nigeria. Driven by high oil prices, technology was devel- A pumpjack Enhanced oil recovery oped to recover oil from increasingly Depending on the precise circum- deep water. Moreover, natural gas technique that the Chinese had used stances of an oil reservoir, approxi- came into view. Originally, striking for centuries to drill for salt. In the 60 mately one-third of the available oil is gas on a drill was considered bad years of its existence, 100 000 m3 of oil generally extracted. The rest stays luck. Locally, you may have been able were retrieved by a pumpjack. behind in the pores of the rock. Using to use it, but exporting it over long Today, oil is extracted from reserves technology, something can still be distances was far too expensive. Here in up to 2.5 km deep water, 6 km done to extract more oil: from rela- too, technological developments below the seabed. This requires the tively simple water injection to press changed the situation. precise drilling of a 6 km deep, 50 cm the oil from the reservoir, to sweeps diameter hole from a drilling platform with surfactants and polymers to Liquefied gas bobbing a few kilometres higher up loosen some of the oil from the rock. With liquefied natural gas technolo- on the sea. Then, at the bottom of the Thanks to high oil prices, these gy, natural gas is compressed to about sea, a construction called a subsea enhanced oil recovery techniques are th 1/600 the volume, and became trans- well head has to be placed on the becoming very interesting. portable over long distances. Recently, well, from which the oil must flow to it also became possible to chemically a production platform which some- Heavy oils and oil sands transform gas on a commercial scale times lies dozens of kilometres away. There are also reservoirs which con- to heavier (liquid) hydrocarbons such This is not to be confused with the tain very heavy, i.e. viscous, oil. as gasoline or diesel fuel (GtL, gas to drilling platform, which drills and Previously, these were not economi- liquid). Thus, huge gas reserves (in constructs the wells and then goes cally developed, but here too, technol- the Persian Gulf, for example, there is away. Production platforms instead ogy can bring about change. But it is a reservoir 10 times as large as contain the processing equipment. not easy and will require large invest- Slochteren in the Netherlands, the Between the reservoir and the plat- ments, also in knowledge building. largest European natural gas field, form, a multitude of problems can Hyperheavy oil is still in abun- estimated at 1.5 × 1012 m3; Russia also occur which must be known and mas- dance. In oil sands and oil shale, holds vast gas reserves) could be used tered. Besides knowhow and technol- reserves of hydrocarbons are stored – to satisfy the hunger for energy. ogy, this requires a lot of money, and the size of many times the amount of All this was possible thanks to the this type of oil field can only be prof- ‘easy’ oil. In Canada, 200 000 m3 of oil development of highly advanced itable if it produces large quantities of are produced daily from excavated tar technology. The first oil well for Shell oil per day: off the coast of Malaysia, sands. This is a costly and difficult in Malaysia, in Miri, was only 140 m a new field has recently been found, process, if only because of the deep, and was drilled in 1910 with a which will produce in four days as extremely low temperatures that pre- 64 Science in School Issue 12 : Summer 2009 www.scienceinschool.org sis_12_RZ:Layout 1 31.07.2009 12:31 Uhr Seite 65 Science topics Tankers and pipelines The technology of oil transportation has evolved ures, and explosions are much larger, with 84% of alongside the oil industry.