Natural gas from the Niobrara Formation was discovered in 1919 al the Beecher Island field in Yuma County, Colorado, but commercial development did not commence until 1972. There are now more than 30 fields located primarily in Yuma County, Colorado and Cheyenne County, Kansas. Biogenic gas is produced from chalk with high porosity but low permeability at the top of the Smoky Hill Chalk Member of the Cretaceous Niobrara Formation at depths ranging from 900 to 2800 feet. The producing area is on the eastern flank of the Denver basin and accumulations were normally on low relief anticlinal closures. The wells are stimulated with a foam fracturing treatment and will deliver from 20 to 300 MCFGPD. The Niobrara and other Upper Cretaceous chalks are considered to be prospective as shallow gas reservoirs over a large area of the Western Interior.