The Formation of Natural Gas

Natural gas is a fossil fuel like oil and coal. This means that it is, essentially, the remains of plants and animals and microorganisms that lived millions and millions of years ago. But how do these once living organisms become an inanimate mixture of gases?

There are many different theories as to the origin of fossil fuels. The most widely accepted theory says that fossil fuels are formed when organic matter (such as the remains of a plant or animal) is compressed under the earth, at very high pressure for a very long time. This is referred to as thermogenic methane. Similar to the formation of oil thermogenic methane is formed from organic particles that are covered in mud and other sediment. Over time, more and more sediment and mud and other debris are piled on top of the organic matter. This sediment and debris puts a great deal of pressure on the organic matter, which compresses it. This compression, combined with high temperatures found deep underneath the earth, break down the carbon bonds in the organic matter. As one gets deeper and deeper under the earths crust, the temperature gets higher and higher. At low temperatures (shallower deposits), more oil is produced relative to natural gas. At higher temperatures, however, more natural gas is created, as opposed to oil. That is why natural gas is usually associated with oil in deposits that are 1 to 2 miles below the earth's crust. Deeper deposits, very far underground, usually contain primarily natural gas, and in many cases, pure methane.

Natural gas can also be formed through the transformation of organic matter by tiny microorganisms. This type of methane is referred to as biogenic methane. Methanogens, tiny methane producing microorganisms, chemically break down organic matter to produce methane. These microorganisms are commonly found in

areas near the surface of the earth that are void of oxygen. These microorganisms also live in the intestines of most animals, including humans. Formation of methane in this manner usually takes place close to the surface of the earth, and the methane produced is usually lost into the atmosphere. In certain circumstances, however, this methane can be trapped underground, recoverable as natural gas. An example of biogenic methane is landfill gas. Waste-containing landfills produce a relatively large amount of natural gas, from the decomposition of the waste materials that they contain. New technologies are allowing this gas to be harvested and used to add to the supply of natural gas.

A third way in which methane (and natural gas) may be formed is through abiogenic processes. Extremely deep under the earth's crust, there exist hydrogen-rich gases and carbon molecules. As these gases gradually rise towards the surface of the earth, they may interact with minerals that also exist underground, in the absence of oxygen. This interaction may result in a reaction, forming elements and compounds that are found in the atmosphere (including nitrogen, oxygen, carbon dioxide, argon, and water). If these gases are under very high pressure as they move towards the surface of the earth, they are likely to form methane deposits, similar to thermogenic methane.

2. Answer the questions on the text:

l) What is the source of natural gas?

2) How many theories of the origin of fossil fuels are described in the text?

3.) How is thermogenic methane formed?

4) What puts a great deal of pressure on the organic matter?

5) Why is natural gas usually associated with oil in deposits that are 1 to 2 miles below the earth's crust?

6) Why do deeper deposits contain primarily natural gas?

7) What type of methane is called biogenic?

8) Where can we find such microorganisms?

9) Where does the formation of this type of methane usually take place?

10) Is it possible to use biogenic methane?

11) How can methane be formed through abiogenic processes?

3. Give English equivalents of the word-combinations from the text:

происхождение ископаемых видов топлива, быть сжатым под землей, со временем, оказывать большое давление, в сочетании с ч-л, разрывать углеродные связи, в отличие от нефти, под земной корой, мельчайшие микроорганизмы, быть лишенным кислорода, таким образом, близко к поверхности, при определенных обстоятельствах, мусорные свалки, собирать, постепенно подниматься, похожий на.

4. Match the words in list A with their definitions in list B. There are two extra definitions in list В which you do not need to use:

List A

1) natural gas

2) a reservoir

3) to remove impurities

4) one Btu

5) fossil fuels

6) biogenic methane

List В

a) the result of decomposition of organic matter under great pressure without air

for a long time

b) gaseous mixture of hydrocarbons

c) to produce in great volumes

d) the result of transformation of organic matter by tiny microorganisms

e) to increase the temperature

f) to refine gas from water, sand and associated hydrocarbons

g) an underground trap made up of porous and permeable rocks

h) the amount of gas that will give energy to heat one pound of water by one

degree at normal pressure

5. Give the summary of the text about natural gas formation using the following word-combinations:

theories of the origin of fossil fuels, thermogenic methane, sediment and debris, break down the carbon bonds, at low temperatures, at higher temperatures, biogenic methane, tiny microorganisms, without oxygen, landfill gas, abiogenic processes, interact with minerals; result in a reaction, forming nitrogen, oxygen, carbon dioxide and other elements.

LESSON 10 (3 часа)

Тема:Технология добычи нефти и газа

Цель и задачи урока:1. Введение и закрепление лексики по теме

2. Работа с устойчивыми словосочетаниями

3. Чтение и перевод текста со словарем

4. Пересказ текста с использованием опорных словосочетаний

Vocabulary

1. reservoir-коллектор

2. to settle- оседать, опускаться

3. silt-ил, наносы

4. layer — слой

5. to pile up — накапливаться