A gas that comprises primarily of methane is known as natural gas.[br] It exists in the vicinity of coal beds as methane clathrates. Natural gas can also be found in marshes or landfills by methanogenic organisms.
Natural gas has become popular as a cleaner alternative to other fuels. Before being used as a fuel, it undergoes rigorous processing. All materials except methane are filtered out. Natural gas is mainly used as liquefied natural gas (LNG) or compressed natural gas (CNG) to fuel vehicles. Natural gas emits 60%-90% less smog producing pollutants and 30%-40% less greenhouse gases than does gasoline.
Natural Gas: Where Is It Found?
Natural gas and its other forms exist primarily at:
- Fossil fields: Natural gas is classified into two types â€“ â€˜casinghead/ associatedâ€™ (found in oil fields) and â€˜non-associatedâ€™ (extracted from exclusive natural gas fields). Russia has the largest reserves of natural gas, followed by Iran, Qatar, Saudi Arabia and the UAE.
- Landfills: Natural gas is generated from the decomposition of waste in landfills. Biogas, another form of natural gas, is produced from agricultural waste.
- Hydrates: Natural gas is also found in the form of hydrates located on offshore continental shelves. Besides, arctic regions, such as Siberia, that have experienced the permafrost also have natural gas reserves. However, these are not suitable for commercial extraction.
Natural Gas: How Is It Extracted?
The extraction of natural gas goes through the following stages:
- Exploration: The search for gas reserves through geophones is the first step. These instruments create a picture of underground structures and highlight areas where gas reserves could possibly exist. The deep natural gas reserves occur below 15,000 feet, while the ultradeep gas resources exist below 25,000 feet.
- Legal formalities: The identification of the location is followed by legal formalities. This includes seeking official permission to drill in that region and extract and sell the natural gas. Also, a permit for establishing a network of pipelines to transport the gas may have to be applied for. Finally, an offshore or onshore exploratory well is drilled in the identified region.
- Onset of commercial production: A newly drilled well, having substantial quantity of marketable gas reserves, is called a ‘development’ or ‘productive’ well. It is upgraded to facilitate commercial production. The extracted natural gas is processed near the well and unwanted components are removed. The processed gas is transported through pipelines.
However, some wells are not commercially viable. These are called ‘dry wells.’ On an average, the deep well success ratio is 25%. The paucity of geological details hinders gas exploration.