Characteristics of Diabase Bed of Xuandong No.2 Mine in Xuanhua-Xiahuayuan Coal Field and Control Action about Coal Bed Gas

摘要

Zhangjiakou Xuandong No.2 Mine is a high gassy mine. Xuandong Diabase intrudes into Jurassic Xiahuayuan coal measure strata with the form of bed rock, which led to the geothermal fields' abnormity and regional thermal metamorphism of coal bed in the study area. The thermal metamorphism of coal is the direct cause of the secondary hydrocarbon-generating. This kind of hydrocarbon generation is the most important factor on current gas content, which plays decisive role on the generation of coalbed gas. Diabase Bed is a good caprock which block the escape route of the gas. The bed rock plays a crucial role on the protection and enrichment of the gas.