Natural gas, a co-product of oil exploitation, has developed in Europe since the end of the 1950s. A fossil energy by nature, natural gas has the immense advantage of being storable unlike electricity and of emitting less greenhouse gases, CO2 in particular, than oil.

Where do we find it? Where does it come from? How is it extracted, transported and stored? These are all questions that make perfect sense in the current geopolitical context.

SirEnergies offers you below some answers that will allow you to better understand this industry linked to the oil activities of multinationals in the energy sector.

What is natural gas?

Composition of natural gas

Natural gas is composed of:

• Methane (CH4): 90 to 95%
• Ethane (C2H6): 4 to 5%
• Nitrogen (N2): 2 to 4%
• Propane (C3H8): ± 1%
• Carbon dioxide (CO2): ± 1%

What is natural gas used for?

Natural gas has several uses:

• Heating residential and tertiary buildings,
• Fabricate of Hydrogen, by cracking methane, in the initial stages of ammonia chemistry and the manufacture of nitrogen fertilizers,
• Producing heat in industrial furnaces and boilers,
• Generating electricity (25% of the world's electricity),
• LNG fuel in road and maritime transport.

What are the types of gas?

Coal gas

Coal gas is a gas produced by coal gasification or during the transformation of hard coal into coke.

Shale gas

Shale gas or Mother rock is a gas of natural origin which is contained, as its name suggests, in marly or argilly-type mother rocks rich in organic matter, some of which have a literal shale structure.

Compact tank gas

Compact tank gas is natural gas extracted by hydraulic fracturing of reservoir rocks. These rocks are so poorly permeable that, to ensure profitable production, they must be fractured.

Biogas

Fermentation, also known as methanization, organic waste releases gas, called biogas, composed mainly of methane and carbon dioxide. This biogas is a combustible gas. of natural and renewable origin, as opposed to natural gas of fossil origin. This gas, whose origin is the decomposition of organic matter, is also called swamp gas, in reference to its formation in a natural environment.

How do you capture and transform natural gas?

Natural gas fields: where are the gas reserves located?

According to the BP report, Statistical Review of World Energy 2021, published on July 8, 2021, the world's natural gas reserves at the end of 2020 amount to 188.1 trillion cubic meters. Notably, Russia, with 37.4 trillion cubic meters, or 20% of the total, has the largest of these “proven” reserves.

However, 40.3% of these global natural gas reserves are located in the Middle East, or 75.8 trillion cubic meters. Geographical area where Iran stands out with 32.1 trillion cubic meters of natural gas, which represents 17.1% of the world's reserves. Then, Qatar has 24.7 trillion cubic meters, or 13.1%. Next comes Saudi Arabia with 6 trillion cubic meters.

Source: The World Sociological Atlas

The ranking below shows the 10 countries with the largest natural gas reserves:

Countries

Natural gas reserves
(in thousands of billions of m3) *

Share of reserves
Global natural gas

1. russia

37.4

19.9%

2. iran

32,1

17.1%

3. qatar

24.7

13.1%

4. Turkmenistan

13.6

7.2%

5. u.s.

12.6

6.7%

6. china

8.4

4.5%

7. Venezuela

6.3

3.3%

8. Saudi Arabia

6

3.2%

9. uae

5.9

3.2%

10. nigeria

5.5

2.9%

Where is natural gas extracted from?

Technically, natural gas is extracted from natural deposits. Its operation is based on three essential steps: exploration, extraction and purification.

Natural gas comes from the slow decomposition of microscopic living organisms such as plankton and algae. It is found in porous rocks in Earth's basements, but also in the ocean floors. Being naturally in gaseous form, it fills the pores and fractures of sedimentary rocks such as sandstones, carbonates, coal beds, and clay shale beds or “shales.”

Natural gas is not available everywhere. The fields are very unevenly distributed and, often, gas and oil are associated in the same geographical areas, or even in the same fields.

Drilling techniques to extract gas

Gas companies use various techniques:

• Vertical drilling, used as early as the 1970s, at the beginning of the exploitation of the first deposits;
• Horizontal drilling, combining vertical drilling to reach the deposit and horizontal drilling to drain the entire extent of the deposit;
• Hydraulic fracturing, used for shale gas fields, which allows the rock to be broken under the action of a liquid at high pressure in order to release the gas trapped there. This technique is forbidden in Europe because it presents too many risks of contaminating groundwater.

Source: Le Point August 5, 2010: “Full gas in the shales” & US EIA

How is natural gas produced and exploited?

Extraction of natural gas

After the exploration phase, once the natural gas is located, gas companies check the viability of a deposit. They therefore proceed with several initial drilling operations in the Earth's crust to reach and delimit the gas pocket, which is generally located at a depth of more than 2 kilometers.

Once the potential of a deposit has been confirmed, impressive drilling infrastructures are installed on land or at sea, vertical to the wellbore. In practice, A drilling tower is erected to maneuver a drill head equipped with very hard diamond teeth, allowing drilling to depths of up to 6 kilometers.

Once the gas pocket is reached, the gas rises up into the borehole pipes, either under the effect of pressure or by pumping. The gas is then stored, processed and transported.

Natural gas transport: gas pipeline and LNG tanker

The natural gas is then transported from the drilling area to distribution networks to which end customers are connected. The means used to transport gas to the distribution network are of two types:

• Of gas pipelines, which are in fact pipelines, making it possible to transport gas under pressure over very long distances, of several tens of thousands of kilometers, on land and under the sea; these infrastructures are very expensive and link producer and consumer countries for a long time.
• Of LNG tankers, to transport natural gas in liquefied form (LNG). In this case, the gas is stored in liquid form and can be delivered anywhere in the world where there are installed LNG terminals regasification.

Natural gas storage

There are several types of natural gas storage :

• Aquifer storage: This type of storage, underground, consists in artificially reproducing a natural gas reservoir. The gas is pressurized and injected into porous cavities containing water. This technique makes it possible to replace, with natural gas, the spaces naturally occupied by water without changing the natural architecture of underground rock cavities. These rock reservoirs are naturally covered by impermeable mineral blocks.
• Saline cavity storage: This type of artificial reservoir is dug by injecting fresh water into a completely impermeable layer of salt located between 500 and 1,500 meters deep. This solution makes it possible to melt the salt and recover it in the form of brine. The gas is infiltrated into the impermeable and non-porous cavity thus formed.
• Depleted reservoir storage: These are exhausted deposits, which are therefore no longer exploited, and which will be used as underground storage spaces, such as aquifers.

Source: Environmental Encyclopedia

Source: Environmental Encyclopedia

• Overhead storage: The gas is liquefied (LNG) by cooling to -160°C and stored in suitable cylindrical tanks. Apart from the port facilities of LNG terminals, this solution is not used in France, where underground storage is preferred.

Source: Types of gas storage tanks, drawing by Patrick Taëron - Archives Larousse

Natural gas: renewable energy or fossil energy?

There are various methods for extracting natural gas. And although the vast majority of natural gas is of fossil origin, because it is generated by the decomposition of organic matter that is several million years old, Natural gas is not renewable energy.

Indeed, just like coal and Oil, natural gas is not inexhaustible since it is consumed more quickly than it is formed in the Earth's geological layers. Its extraction, like that of other fossil fuels, causes considerable damage to the environment due to the installation of highly polluting industrial installations on extraction sites.

Natural gas only allows a 25% reduction in emissions compared to oil.

Note that there is an alternative to fossil gas: renewable natural gas resulting from methanization, i.e. the decomposition of organic matter in methanizers. This gas is considered to be green and renewable energy. It should be noted that this gas remains marginal in total consumption in France.

Where does the gas consumed in France come from?

In France, the Lacq deposit, which once supplied up to 50% of French consumption, is still partially active and supplies only a few local businesses marginally.

Today, France imports all of its natural gas needs. This gas comes mainly from Norway. Russia thus comes in second position, followed by Algeria, Nigeria and the Netherlands.

What is the future of natural gas?

The war that Russia is waging in Ukraine has highlighted the very strong dependence of EU economies on natural gas gas pipeline from Russia. Regardless of the measures taken in the emergency of the Ukrainian crisis, the EU must prepare for the future and protect against the risk of cuts gas imports threatening its democratic political model.

If Europe wants to give gas a future, it must now invest in port infrastructure to develop LNG (liquefied natural gas) and in new gas pipelines to diversify its onshore supplies from Russia.

PO Statistical Review foresees a significant drop in the use of natural gas in the coming decades, or even a total cessation of its use by 2050.

Currently, the Ministry of Energy Transition and ADEME push industries that consume a lot of heat, such as the food industry or the chemical industry, to acquire biomass boilers to decarbonize their sites. These subsidy programs, BCIAT and DECAR INDUS, are part of the industrial recovery plan decided by the public authorities.

Natural gas is considered by many to be a transition energy.

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