东胜矿区地质构造演化及瓦斯赋存规律研究

Study on Geological Structure Evolution and Gas Occurrence Law in Dongsheng Mining Area

运用区域地质演化理论,研究东胜矿区不同构造运动阶段应力场演化及其对煤层瓦斯生成、运移、保存条件的控制特征,探讨矿区内的断层、埋深、顶底板岩性和水文地质条件等对瓦斯的控制作用。研究结果表明:1)东胜煤田位于华北地台鄂尔多斯台向斜北缘,经历了太古代整个地质历史时期的演化过程,其间发生了集宁运动和乌拉山运动及相伴随的多旋回岩浆活动和变质作用,元古代色尔腾山旋回使其进一步扩大和稳定团结,白云鄂博旋回线型坳陷的似盖层沉积和褶皱使其得以巩固和最终形成地台。2)东胜矿区延安组煤层变质程度低、含气性能差。中侏罗统延安组沉积后,连续沉积直罗组、安定组后,晚侏罗世鄂尔多斯盆地呈隆升阶段,缺失上统芬芳河组及下白垩统地层,由此造成延安组煤层暴露在甲烷风化带,遭受古风化带侵蚀,使已经形成的烃类气体逸散。3)综合考虑煤层发育程度、地质构造特征、水文地质及埋藏深度等条件,认为构造运动及成煤物质两个条件是本区煤层瓦斯含量低的主因。

Using regional geological evolution theory to study the evolution of stress field in different tectonic movements in Dongsheng mining area and the control characteristics for coal seam gas generation and migration and preservation condition. Discusses the control effect of rock and hydrogeological conditions on the buried floor and roof of the mining area. The results indicate that Dongsheng coalfield is located at the north of northern China platform of Ordos,and has experienced the evolution process of the whole archaeozoic geological history,meanwhile the activities of Jining movement,Ural mountain movement and the associated polycyclic magmatic activity and metamorphism occurred. Proterozoic the colerton mountain spins back to further expand and stabilize unity,the stratum sedimentary and folding of Baiyun Ebo in linear depression have enabled it to consolidate and eventually form the platform. The deterioration degree of coal seam in Yanan formation is poor in Dongsheng mining area. After the middle Jurassic Yan An formation and continuous deposition of Zhiluo Anding Formation,the late Jurassic ordos basin is in the uplift phase with the absence of the aromatic river formation and lower cretaceous strata. In this way,the coal seam of Yan An formation is exposed to methane weathering zone,which is eroded by ancient weathering,and the formation of hydrocarbon gases is dissipated. Considering conditions of the degree of coal seam development and characteristics of geological structure and hydrogeology and burial depth,it is believed that the two conditions of tectonic movement and coal forming are the main reasons for low gas content in coal seam.