中国高煤阶煤层气成藏特征

国内学者普遍认为高煤阶煤层由于其演化程度较高、割理不发育、煤层的渗透率极低而低估了勘探前景，以至于形成了煤层气勘探的“禁区”。中国地质条件和含煤盆地的构造活动要比美国复杂得多，煤层气的生成和富集有着自身的特点，而且多数煤层在其沉积后经历了多个期次、多个方向的应力场改造，而且大部分高煤阶形成与岩浆热变质事件有关。这些因素使得高煤阶的气体成因、物性特征、水文地质条件、含气性和成藏过程等都与低煤阶和国外高煤阶明显不同，有可能形成煤层气高产富集区，形成煤层气勘探的有利地区。

THE CHARACTERISTICS OF HIGH RANK COALBED METHANE RESERVOIR

It is generally considered by domestic geologists that the exploration prospects of high rank coalbed methane is low estimated owing to it with high evolution degree, undeveloped cleat and very low permeability, thus forming the “Forbidden Zone” of exploring coalbed methane. The geological conditions and structure background of coal bearing basins in China are more complicated than those in USA. The coalbed methane generation and gathering are of China’s characteristics. Many coalbeds underwent multi period and multi direction stress field transformations after sediment and most of high rank coal formation is relative to magma thermal metamorphism. These factors make the origins, physical property, hydrogeologic conditions, gas bearing characters and reservoiring processes be obviously different from those of low rank coal and overseas. It is possible to find better location with high production in high rank coalbed methane basin. (Financed by the 973 Program Project, No. 2002CB211705)