Structural-Hydrological Dynamic Characteristics And Its Control Mechanism On Coalbed Methane Reservior

This dissertation chose the middle-southern region in the eastern margin of Ordos Basin,one of the key areas for coalbed methane exploration and exploitation in China,as the study area,and took the scientific issues in structural-hydrological dynamic control on coalbed methane reservoir as the main research content,the characteristics of regional tectonic evolution and its control on structure development and evolution in the study area were explored,by comprehensive analysis and summary of regional tectonic background and evolution,combined with field observation and analysis of typical structures,NW-SE direction compression of Yanshanian was most intensely,tectonic deformation gradually weakened from the eastern margin to the inside of the basin,and coal seam is a monoclinic with NE strike and trends to NW direction.After analyzing the control mechanism of structure on groundwater dynamic field,we divided the study area into five hydrogeological units,of which CBM occurrence characteristics and control mechanism of structural-hydrological dynamic were revealed;Characteristics of the water chemistry field and its indication for CBM occurrence of Daning-Xiangning and Hancheng area were studied.The stress calculation method based on logging data for the coal reservoir was explored and a relatively complete technical process was formed.The horizontal and vertical change and distribution law of the maximum,the minimum horizontal principal stress and the vertical principal stress in Daning-Xiangning area were discussed,as well as the variation laws of transformation depth of horizontal and vertical stress,the results indicated that the vertical principal stress has a general variation trend of low in east and high in west,stress is relatively low in fold axis trace and fault zone;The maximum and minimum horizontal stress has a general waving variation trend of low ~ high ~low ~ high from the east to the west,it was significantly affected by geological structure;The transformation depth of horizontal and vertical stress gradually increases from the east to the west in general.Coal reservoirs with high permeability in Daning-Xiangning area were predicted and evaluated by analyzing in situ stress and the development of the dominant fracture,high and middle permeability area of No.5 coal seam in the central block located in Mingti-Yangjiahe region,high permeability area located in Mingzhu-Maojiazhuang in the south block,both with a NW trending.The dissertation contains 79 figures,12 tables and 245 references.