Changes

Coalbed methane, which not too long ago was considered an unconventional type of gas accumulation (and the cause of deadly accidents in underground coal mines), is now being produced profitably in several basins in the United States (about 7% of the total United States natural-gas production) and in Australia and is being investigated in other parts of the world. Natural gas from tight-sand reservoirs is also becoming a substantial part of the total natural gas produced in the United States. Lesser production has been obtained for many years from organic black shales and from basin-centered reservoirs. Production of the natural gas in methane hydrates and in solution in geopressured formation waters will probably not be economically viable for many years, if ever. These last two occurrences of natural gas may be better called speculative.

Coalbed methane, which not too long ago was considered an unconventional type of gas accumulation (and the cause of deadly accidents in underground coal mines), is now being produced profitably in several basins in the United States (about 7% of the total United States natural-gas production) and in Australia and is being investigated in other parts of the world. Natural gas from tight-sand reservoirs is also becoming a substantial part of the total natural gas produced in the United States. Lesser production has been obtained for many years from organic black shales and from basin-centered reservoirs. Production of the natural gas in methane hydrates and in solution in geopressured formation waters will probably not be economically viable for many years, if ever. These last two occurrences of natural gas may be better called speculative.

==See also==

==See also==