Natural Gas: Fundamentals

Natural gas is a combustible gaseous mixture of hydrocarbons, mostly methane. It is produced from wells drilled into underground reservoirs of porous rock. Natural gas withdrawn from the well may contain liquid hydrocarbons and nonhydrocarbon gases. The natural gas is separated from these components near the site of the well or at a natural gas processing plant. The gas is then considered “dry” and is sent through pipelines to a local distribution company, and ultimately, to the consumer. Dry natural gas is also known as consumer-grade natural gas. In addition to natural gas production, the U.S. gas supply is augmented by imports, withdrawals from storage, and by supplemental gaseous fuels.

The search for natural gas begins with geologists. They locate the types of rock that are known to contain gas and oil deposits.

Today their tools include seismic surveys that are used to find the right places to drill wells. Seismic surveys use echoes from a vibration source at the earth’s surface (usually a vibrating pad under a truck built for this purpose) to collect information about the rocks beneath.

Seismic Survey Process

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 along with 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 colorless, odorless and tasteless, mercaptan (a chemical that has a sulfur like odor) is added before distribution, to give it a distinct unpleasant odor (smells like rotten eggs). This serves as a safety device by allowing it to be detected in the atmosphere, in cases where leaks occur.

Most of the natural gas consumed in the United States is produced in the United States. Some is imported from Canada and shipped to the United States in pipelines. Increasingly natural gas is also being shipped to the United States as liquefied natural gas(LNG).

Approximately 22 percent of the energy consumption of the U.S. comes from natural gas. Slightly more than half of the homes in the U.S. use natural gas as their main heating fuel.

Seismic Data in 3D

Natural gas is also an essential raw material for many common products, such as: paints , fertilizer, plastics, antifreeze, dyes, photographic film, medicines, and explosives. We also get propane when we process natural gas. Propane is the fuel many of us use in our barbecue grills.

Natural gas has thousands of uses and industry depends on it. It's used to produce steel, glass, paper, clothing, brick, and electricity.

Homes use it too. More than 62.5 percent of homes use natural gas to fuel stoves, furnaces, water heaters, clothes dryers and other household appliances. It is also used to roast coffee, smoke meats, bake bread and much more.

Source: Energy Information Administration