韩城矿区煤层气富集的构造控制与开发模式研究

Development mode and tectonic control of CBM enrichment in Hancheng Mining Area

韩城矿区地质构造复杂,构造对煤层气的控制作用明显。为了揭示构造对韩城矿区煤层气富集与开发的影响,通过挖掘整理韩城矿区基底沉降史,厘定煤层气成因、划分煤级平面分布,分析含气量与构造样式、煤层埋深的关系。研究发现,韩城矿区浅部受基地抬升与构造应力共同作用,煤层气为次生生物成因气叠合热成因气;深部经历深成变质作用为典型的高煤阶热成因气。受控于不同构造样式与现今埋深,北部层滑构造导致的构造煤发育,含气量较南部高、中深部含气量较浅部高。基于构造控制的煤层气赋存特征、煤体结构和应力环境的复杂性分析,提出东北区的桑树坪井田、下峪口井田,东南区的象山井田构造煤发育,建议采用"压力-应力协同释放为主的矿井卸压抽采模式";西部的王峰和薛峰井田含气量高、煤体结构相对完好,建议采用"排水降压为主的地面井降压开采模式"。

The geological structure of Hancheng Mining Area is complex, and the controlling effect of structure on CBM is obvious. In order to reveal the influence of structure on the enrichment, accumulation and development of CBM in Hancheng Mining Area, the basement subsidence history of the area is studied, the genesis of CBM is determined, the plane distribution of coal rank is divided, and the relationship between gas content and structural style and buried depth of coal seam is analyzed. It is found that the shallow part of the area is affected by base uplift and tectonic stress, CBM is secondary biogenic gas superimposed thermogenetic gas, and deep metamorphism is a typical high coal rank thermogenetic gas. Controlled by different tectonic styles and present burial depth, the gas content of the structural coal caused by the layer slip structure in the north is higher than that in the south, and the gas content in the middle and deep part is higher than that in the shallow part. Based on the analysis of the occurrence characteristics of CBM controlled by structure, the complexity analysis of coal body structure and stress environment, it is proposed that structural coal is developed in Sangshuping mine field and Xiayukou mine field in northeast region and Xiangshan mine field in southeast region, and that mine pressure relief pumping mode based on pressure-stress synergistic release should be adopted. In Wangfeng and Xuefeng mine fields in the west, the gas content is high and the coal structure is relatively intact, so it is suggested to adopt the surface well depressurization mining mode based on drainage-depressurization.