There is a natural fissure system in the coal.The formation of fissure system in the coal and the coalification are close related to the structural characteristics there.

• 煤层具有天然裂隙系统,煤中的裂隙系统(割理)的形成、煤化作用与当地的构造特征密切相关,裂隙系统的好坏是开采煤层气的关键。