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Natural gas processing refers to the steps necessary to take natural gas from its extracted state to a consumer-safe, usable product. Not all gas is alike in chemical composition, meaning that multiple separate processes may be necessary to refine gas into a pipeline-ready product. Natural gas processing is essential to the production of usable gas, but does involve some environmental and safety hazards.
The extraction of natural gas is done through three types of wells, which may affect the type of natural gas processing necessary to create a finished product. Oil-well gas needs to be processed to separate the gas from crude oil, while gas from condensing wells needs to be processed to remove water and hydrocarbons. True natural gas wells produce a product called unassociated gas, which may require less processing before being placed into pipelines.
After the initial separation is complete, natural gas processing will depend on the chemical substances present in the extracted gas. One of the most common steps is the “sweetening” of gas with high levels of hydrogen sulfide. Though some natural gas is naturally low in this compound, it must be processed out of some sources since it is highly flammable and explosive. Sweetening is generally done by processing the gas with an substance, typically an amine solution, that absorbs the hydrogen sulfide until it reaches safe levels.
Many steps in natural gas processing are done less to create safer gas, and more to extract valuable byproducts from the initial substance. Butane, propane, and ethane can all be extracted from some sources of natural gas, and are profitable products in themselves. The sweetening process also allows for the collection of sulfur, which is extremely valuable. Other substances removed from gas during processing are discarded for a variety of reasons and using several methods. Water, for example is typically dehydrated out of the gas, while radon, which is radioactive, needs to be removed and disposed of as a biohazard.
Natural gas processing is done through a natural gas plant, which is an interconnected system of wells and processing chambers. These large plants consist of pipelines through which the gas can be directed for specific processing treatments. At each stage, testing may be performed to ensure the product meets industry or government standards for purity and composition. Processing plants are typically located at or near the site of wells, though large natural gas systems may have additional check-point plants strategically placed along the pipeline.
Since natural gas processing involves the removal of polluting and often dangerous materials from gas, the question of pollution management is critical to the future of the industry. How toxic substances, such as sulfur, butane, and toluene, are removed, managed, released, and stored are carefully regulated by many governments. In some regions, processing plants are subject to emissions limits, with sanctions and fines issued for violations.