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How can natural gas be a source of commercially useful helium?

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Multiple large offshore petroleum oil rigs with cranes and equipment stand in the ocean, connected by walkways above the water. — petroleum Liquid petroleum (crude oil)—which is refined into gasoline, diesel, heating fuels, asphalt, plastics, and other useful chemical compounds—is often extracted from the ground using a series of drills and pumps.

Natural gas serves as a primary source of commercially useful helium because certain natural gas deposits contain significant concentrations of the element, sometimes reaching up to 7.6 percent. While helium and natural gas are geologically unrelated—helium is produced by the radioactive decay of thorium and uranium isotopes—they often become trapped together within the same underground reservoirs.12

To extract helium for commercial use, the gas is isolated from the natural gas mixture through a process of liquefaction. By subjecting the mixture to low temperatures and high pressures, the other components of the natural gas are liquefied, leaving the helium behind. Further purification, such as the adsorption of remaining gases on cooled, activated charcoal, can increase the purity of the helium to 99.995 percent.1