中国煤储层岩石物理学因素控气特征及机理

Geological Controls and Their Mechanisms of Coal Reservoir Petrography and Physics of Coalbed Methane Occurrence in China

基于全国主要矿区或勘探区统计资料，总结了煤级、煤岩类型、显微组分组成等煤的岩石物理学因素与煤层含气量、吸附性、渗透性等之间的关系，探讨了煤储层岩石物理学特征的控气作用机理．发现煤级－含气量的“包络线”具有阶段性演化规律，最大含气量的显著变化与煤化作用阶跃高度一致，煤储层含气量较高的地区沿纬向等间距展布且与较高煤级煤分布区吻合，煤的兰氏体积与镜质组含量关系中存在一个镜质组含量临界值．指出不同煤化作用阶段控气作用的实质在于煤物理结构和化学结构的演化，沉积作用控气的思路对煤储层渗透率非均质性预测具有一定实践意义．

Based upon the data from major coal mining and prospecting districts in China, the correlation of coal petrological and physical factors such as coal rank, lithotype and maceral to the coal methane content, absorption and permeability was summarized, and their controlled gas mechanisms were discussed. It has been found that the enveloping line of the average methane content to coal rank develops in the coalification stages, that the remarkable developments of the maximum average methane content coincide greatly with coalification jumps, that the areas with higher average methane content occur in a approximately equal latitudinal gap, and that there is a critical vitrinite content in the correlation of coal Langmuir's volume to vitrinite content in coal reservoirs. It is suggested that the development of coal physical and chemical structure is the reason why the coalbed methane occurrence is controlled in various coalification stages, and that the concept on the coalbed methane controlled by coal sedimentation would be practically valuable in some degree for predicting the heterogeneity of coal reservoir permeability.