Microcosmic Fracture System Study Of Tectonically Deformed Coal

Microcosmic fracture system is closely related with coal reservoir permeability, affecting coalbed methane enrichment and output, the basis of coal reservoir characteristics research and coalbed methane exploration, development and evaluation. Based on macro and microscopic observation, CT scanning and data processing, output stress-strain analysis of the different types of tectonically deformed coal, this paper study microcosmic fracture system characteristics of tectonically deformed coal, the following results:1 From the perspective of geometry, single fracture: straight type, curved type, twist type, jagged type, parallel simple combination: same length type, en echelon type, pay check simple combination: intersection type, cutoff type, split type, mesh medium combination: gridiron pattern, diamond type, irregular type, tree type, complex combination: microgroove type, flow variant type, damage type, it is concluded that three dimensional crack is extension and development of two-dimensional cracks. 2 Normal fault on disk, fault fracture zone, thinning belt of normal fault on disk, away from fault zone under brittle fracture deformation environment; normal fault footwall, thinner plate on normal fault belt, the shear zone in the fault under shear deformation environment; away from the fault zone ductile deformation environment. Combining with the conclusion 1 about summarizing of geometry characteristics, classifing fracture system characteristics of different tectonic background under the brittle fracture, shear, ductile deformation environment. 3 In every deformation series of brittle fracture, shear, ductile deformation series, fracture system is from a single crack parallel to the simple combination to cross check simple combination to complex combination of features with the increase of the deformation degree, and fracture system change from a single fracture to the dense type and damage type of complex combination in brittle deformation environment, given priority to with simple medium composition and complex combination type in shear deformation series, given priority to with complex combination type in ductile deformation environment. 4 Four additive effect are summarized brittle fracture and shear deformation, brittle fracture and ductile deformation environment, shear and ductile deformation environment, brittle fracture, shear and ductile deformation environment.