7BARR K, KIM A. A guideline to optimize drilling fluids for coal- bed methane reservoirs[C]. Denver: [s.n.], 2009.
8SPADY D W, LLC. Urban operations: drilling and completing a gas well on a downtown university campus[C]. Amsterdam: [s.n.], 2005.
9CLARK J, CERA. Natural gas poised to overtake oil use by 2025[J]. Oil & Gas Journal, 2004, 102(9): 20-21.
10GUNTER W D, MAVOR M J, ROBINSON J R. CO: storage and enhanced methane production: field testing at Ferm-Big Valley, Alberta, Canada, with application[C]. London: Elsevier, 2005: 413-422.