关键词: 无烟煤, 煤层气, 成藏, 产气机理, 评判指标

Abstract: The necessary conditions for coalbed methane (CBM) reservoir and gas production include gas prone organic matters,gas storage space,absorbing power,flow channels,driving capacity and coal reservoir stimulation.At present,the diagnostic criteria for gas reservoir mainly include isothermal adsorption property,flowing transferability,gas content,absorbing and driving power.The adsorption constant, permeability,gas content and reservoir pressure are the key indexes for evaluating the potential of a CBM reservoir.In terms of these four indexes,the normal anthracite has no potential for gas reservoir and production.The evaluation result of Qinshui anthracite with middle ranked coal theory shows that it has good sedimentary tectonic and geothermal history.The evaluation with the four indexes shows that anthracite in Qinshui Basin has good commercial gas production.The crustal movement, magma intrusion and sedimentation are very well stacked during the coalification process in Qinshui Basin.The four elements are attributed to the commercial production of CBM in Qinshui anthracite coal,including shallowly buried coal seam resulting from crustal movement upward before the second gas generating rush,short-time strong geothermal coal alteration due to Mohole layer up-bending,regionally distributed extensional crustal stress and geological structure for water pressurization.

Key words: anthracite coatbed, coalbed methane, reservoir generation, gas production mechanism, diagnostic index