Millions of years ago, the remains of plants and animals decayed and built up in thick layers. This decayed matter from plants and animals is called organic material it was once alive. Over time, the mud and soil changed to rock, covered the organic material and trapped it beneath the rock.
Pressure and heat changed some of this organic material into coal, some into oil (petroleum), and some into natural gas tiny bubbles of odourless gas. The main ingredient in natural gas is methane, a gas (or compound) composed of one carbon atom and four hydrogen atoms.
In some places, gas escapes from small gaps in the rocks into the air; then, if there is enough activation energy from lightning or a fire, it burns. When people first saw the flames, they experimented with them and learned they could use them for heat and light.
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Scientists and engineers explore a chosen area by studying rock samples from the earth and taking measurements. If the site seems promising, drilling begins. Some of these areas are on land but many are offshore, deep in the ocean.
Once the gas is found, it flows up through the well to the surface of the ground and into large pipelines. Some of the gases that are produced alongwith methane, such as butane and propane (also known as ‘by-products’), are separated and cleaned at a gas processing plant. The by-products, once removed, are used in a number of ways. For example, propane can be used for cooking on gas grills.
Because natural gas is colourless, odourless and tasteless, mercaptan (a chemical that has a sulfur like odour) is added before distribution, to give it a distinct unpleasant odour (smells like rotten eggs). This serves as a safety device by allowing it to be detected in the atmosphere, in cases where leaks occur.