Natural gas before the natural gas can be transported. Natural gas extracted from oil wells is called casinghead gas (whether or not truly produced up the annulus and through a casinghead outlet) or associated gas. The natural gas industry is extracting an increasing quantity of gas from challenging resource types: sour gas, tight gas, shale gas, and coalbed methane. There is some disagreement on which country has the largest proven gas reserves. Sources that consider that Russia has by far the largest proven reserves include the US CIA (47 600 km³), the US Energy Information Administration (47 800 km³), and OPEC (48
Substitute natural gas Substitute natural gas Substitute natural gas (SNG), or synthetic natural gas, is a fuel gas that can be produced from fossil fuels such as lignite coal, oil shale, or from biofuels (when it is named bio-SNG) or from renewable electrical energy. The Great Plains Synfuels Plant injects approximately 4.1 million m/day of SNG from lignite coal into the United States national gas grid. The production process of SNG at the Great Plains plant involves gasification, gas cleaning, shift, and methanation. China is constructing nearly 30 nos massive SNG production plants from coal / lignite with aggregate annual capacity of 120