大宁-吉县地区的煤层气地质条件复杂，主要表现在3个方面：①山西纽煤层厚度变化大，有明显的尖灭变薄现象；②与煤层气藏保存直接有关的煤层顸、底板的岩性与厚度有明显变化，造成控制煤层气富集与高产的因素组合关系复杂、煤层气藏类型较多和煤层气藏边界复杂；③水文地质条件多样。通过对含煤岩系沉积特征和古生物标志分析指出，该区含煤岩系是在稳定的地台构造背景上发育的一套海湾潮坪-三角洲充填沉积，从不同沉积环境条件下形成的煤储层岩石物理的特征看，三角洲沉积环境条件下形成的煤储层渗透性比较好。

The coalbed methane （CBM） geologic condition in Daning-Jixian region is very complex, it reveals into three aspects as follows ： ①The thickness of coal seam of shan＇xi formation is changeable, and there exist obviously thinning or thinning out. ②The changes oflithotypes and thickness of the floor and roof of coal seam, which are directly concerned to the preservation of CBM have brought about such changes as more combinations during factors which control the enrichment and high-production of CBM and more types of coal gas pools and the complex boundaries of coal gas pools. ③The hydrogeologic conditions of the region are diverse. The deposit environment has great control of thickness and structure of coal seam and physical property of coal reservoirs and the lithotypes of wall rock. Thinking the sediment characters and paleontologic indexes of the coal-bearing strata in the region, the deposit environment of the coal-bearing strata in the region are estuarine deposit→tidal flat deposit→deltaic deposit, which are under the background of a stable platform structure. Seeing from the petrophysics characters of coal reservoirs that formed in different deposit environments, the permeability of coal reservoirs are much better in deltaic deposit.