Natural Gas 101: An Introduction

Composed primarily of methane (CH4) with lesser quantities of other hydrocarbons, natural gas is the cleanest fossil fuel to burn for heating, electricity generation, or additional energy needs including CNG powered vehicles and other chemical processes.

Formed over millions of years through the transformation of buried marine organisms, extensive stores of natural gas are trapped in reservoirs under a sedimentary rock throughout the world.

Natural Gas Extraction

Conventional natural gas extraction can be done by drilling through the impermeable caprock sitting above large reservoirs and then capping the pipe with a well. Modern extraction techniques are now also available for capturing alternate forms of natural gas including gas hydrates, shale gas, sour gas, tight gas, coalbed methane, and associated gas. Associated gas is a type of natural gas found alongside oil.

Renewable natural gas (RNG) is an additional type of natural gas captured from agricultural or other biomass waste facilities.

Methane Content and Gas Quality

Natural gas is typically categorized based on methane content. The higher the percentage of methane, the better the quality of the gas.

Biogenic gas, also known as dry gas, contains 95% methane or better. Biogenic gas is generally found at shallower depths, where bacterial decay was able to take place more slowly.

In comparison, thermogenic gas, also known as wet gas, is found at lower depths where the formation was accelerated by high temperatures. The thermogenic gas production process created additional compounds of ethane and butane along with the methane, giving way to a methane content lower than 95%. To extract dry natural gas from wet natural gas, the natural gas liquids (NGLs) of ethane and butane must first be separated and sold separately for other industrial purposes.

Creating Pipeline Quality Gas

Both biogenic and thermogenic gas must be processed before being injected into the natural gas distribution network. Purification removes impurities that include oil and condensate, water, NGLs, sulfur, and CO2.

Natural Gas Transport and Distribution

Most natural gas is transported underground through a network of pipelines. Pipelines that run from the extraction point to the processing plants are called gathering lines, and then feeder lines run from processing plants to storage facilities and end-users.

Natural gas can also be transported above ground or across the sea by first liquifying the gas into LNG and then utilizing specialized trucks or oceangoing tankers.

Natural Gas Production Growth in the United States

Natural gas is an incredibly reliable and available domestic fuel source, with US dry natural gas production exceeding total consumption by 10% in 2020.

To complement the rapid growth of conventional natural gas production in the United States, renewable natural gas (RNG) has seen a significant increase in capture and purification of late. There are now well over one hundred renewable natural gas facilities across the country, a number that has tripled over the last five years alone.

Moving forward, both conventional and renewable natural gas are well-positioned to play vital roles in America’s energy needs.