Natural gas comes from the remains of ancient plants and microorganisms that were buried, heated, and compressed deep underground over millions of years, forming gas-rich rock layers and reservoirs beneath Earth’s surface.

What natural gas actually is

  • Natural gas is a fossil fuel made mostly of methane (CH₄), a simple hydrocarbon.
  • It often occurs together with crude oil and sometimes with coal in the same geologic regions.
  • It is colorless and naturally odorless; the “gas smell” in homes is added later for safety.

How natural gas forms (millions of years)

  1. Tiny marine plants and microorganisms live in ancient seas and lakes. When they die, they sink and mix with mud and sand on the seafloor.
  1. Over time, more and more sediment piles on top, burying this organic-rich layer deeper underground.
  2. Increasing heat and pressure slowly transform the buried organic matter into hydrocarbons—oil and natural gas—in a process called thermal maturation.
  1. The gas can migrate through porous rocks until it is trapped under impermeable rock layers, forming underground reservoirs.

You can think of it like a slow-motion pressure cooker deep underground, turning ancient life into combustible gas over geological time.

Where natural gas is found underground

  • Natural gas is found in rock formations deep below Earth’s surface, often in the same regions as oil.
  • It can occur:
    • In large, open spaces in rock (“conventional” gas reservoirs).
* Locked in tiny pores of shale, sandstone, or other tight rocks (“shale gas” or “tight gas,” known as “unconventional” gas).

* In coal seams (coal-bed methane).
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Type of natural gas Where it sits Key feature
Conventional gas Large cracks and spaces in porous rock, capped by impermeable rock.Easier to extract with traditional drilling.
Shale / tight gas Tiny pores in shale or very tight sandstone/carbonate rocks.Requires advanced techniques like horizontal drilling and fracking.
Coal-bed methane Trapped in coal seams associated with ancient swamps.Linked to coal deposits; can be produced from coal mines.

How humans get natural gas out

  • Geologists look for likely gas-bearing formations using seismic surveys and geologic studies.
  • Wells are drilled down into the targeted rock; in some cases, wells go horizontally through shale layers to access more gas.
  • In unconventional formations, hydraulic fracturing (“fracking”) is often used to crack the rock and let the gas flow.
  • The gas from the well is collected, processed to remove water and impurities, and then sent through pipelines to homes, power plants, and industries.

Where in the world natural gas comes from today

  • Natural gas reservoirs exist on land and offshore, beneath the ocean floor, in many parts of the globe.
  • A few countries hold especially large reserves: Russia, Iran, and Qatar together account for around half of the world’s known reserves, while the United States, United Arab Emirates, Venezuela, Saudi Arabia, Nigeria, and Algeria also have major resources.
  • In the United States, most of the natural gas used domestically is produced within the country, heavily from shale and tight gas formations, with some additional imports and LNG.

Quick recap (TL;DR)

  • Natural gas comes from ancient organic matter (mostly marine plants and microorganisms) buried and transformed by heat and pressure over millions of years.
  • It accumulates in deep underground rock formations—sometimes in big open spaces, sometimes locked in tiny pores—on land and under the sea.
  • We locate these formations, drill wells, and sometimes use fracking to release the gas, then process and pipe it to where it’s used.

Information gathered from public forums or data available on the internet and portrayed here.