Natural gas field

As a natural gas field in a natural gas deposit is referred to in porous sedimentary layers of the earth's crust, which is economically viable or is extracted from the gas already. For the most part they arise from marine sediments of marginal seas, in Central Europe, for example, from the so-called Zechstein Sea or the late stages of the Tethys Sea.

Gas fields presuppose the existence of sufficiently porous sediments, which can serve as reservoir rock for the gases and usually also for other hydrocarbons, such as petroleum. The largely biogenic gases collect in pores or crevices beneath an air-impermeable layer. At storage types, a distinction is saddle-shaped bulges under a sealing layer or slanting deposits with seal on cross- layers of salt dome flanks or in deportations.

Oil or gashöffige areas are first vorerkundet by geological and geophysical exploration, drilling and later follow in the success of the production well. The promotion to the surface is done by the gas pressure or (more rarely) by injecting salt water into the ground.

Formation of deposits

Natural gas produced by similar processes such as petroleum, but more than this one, and goes back to biogenic deposits warm era. When it occurs along with oil, it is solved in this or superimposed over it. It is formed under high pressure and temperature from the sludge of dead micro-organisms of the oceans, from algae or plankton when they are covered by sediments of air. Tectonic processes (ceiling, mountain building, etc.), the gases may in other porous rocks " migrate " and to gather underneath sealing layers. Larger quantities of natural gas have emerged locally ( without substantial migration) by bacterial decomposition of organic matter, such as under the foothills of the Alps in the Neogene (before about 20 millions ).

Natural gas deposits are usually mixed hydrocarbon fields, the biogenic gases in variable composition and often contain petroleum. The latter alone is hard to occur, pure gas fields but often because the gas can migrate more easily due to the lower density.

The largest known gas fields are located in Russia and the U.S.; high flow rates also achieve Canada, Iran and Norway. These five States in 2008 accounted for about 52% of the global production of 3,065 billion cubic meters. Large deposits are also in some CIS countries of Central Asia (especially Turkmenistan), in the northern regions of Siberia and on the Pacific coast of Sakhalin, in countries of the Persian Gulf like Saudi Arabia, Qatar and Iran, Algeria and South America. The largest European deposits are under the North Sea: the Norwegian Troll field, the Dutch Uithuizen and some fields in the direction of England. More recent finds were, inter alia, known from Bolivia and central Ukraine, while, for example those in Lower Saxony are approaching the end.

The world's known gas reserves amounted to 2007, according to BGR about 180,000 billion cubic meters, which would be enough with consistently adopted world consumption last for about 60 years. At the Reserves Russia holds 26 percent, 15 Iran and Qatar 14 percent, followed by Central Asia and the USA. One problem in the estimation of future gas production is that - unlike oil fields - a sudden decline in fertility, which applies to individual fields as well as the statistics of world reserves.

Composition

Natural gas is a gas mixture the composition of which depends strongly on the location. but the greater part always makes methane ( swamp gas, CH4). The incorporation of higher hydrocarbons such as the alkanes ethane, propane, butane and ethene will vary as well as from water vapor, carbon dioxide, small amounts of hydrogen sulfide and less reactive, inert gases (helium, other noble gases and nitrogen). Natural gas with a higher proportion of pressure-liquefied gases is called wet natural gas.

For example, North Sea gas average of 89% methane and 8 % of other alkanes, whereas Siberian gas contains 97-99 % methane. Gas type L in turn has 11% of inert gases.

History

When the first discovery of natural gas was carried out, is uncertain, but probably already in volcanic events in ancient times. In Europe and the U.S., the targeted promotion dates back to the 19th century. The first discovery in Europe in 1844 in Vienna on the grounds of the East Railway Station. From a large scale was in 1892 in Wels (Upper Austria ) deposits found in well drilling, where it was soon promoted from 150 drill holes and is to this day.

Larger areas of promotion of the early 20th century were the Vienna Basin, the gas deposits in Lower Saxony and the large fields in North America (USA and Mexico), which soon outstripped the yield far in other regions. 1938 in North America about 35 billion standard cubic meters (Nm ³) promoted in Europe more than a tenth. During World War II the production in Russia has been greatly increased, and in 1956 amounted to 10-11 billion Nm ³, those of the U.S. ³ 260 billion Nm. In Canada and Italy accounted for 1956 of 4-5, to Mexico and Indonesia 3-4 billion Nm ³, ³ on Austria and Brunei each about 1 billion Nm.

In Germany (mainly Lower and Upper Bavaria ) promotion 1975-1980 with up to 20 billion Nm ³ (1979 20.3 ) was the highest, but has since been returned. The recoverable with today's technology funding Germany's natural gas reserves are estimated at 218 billion cubic meters, the economically / technically not currently recoverable resources to ~ 200 billion cubic meters. In Austria they are about one quarter of these values ​​, in Switzerland significantly less.