The Development Law Of Structure Fracture And The Influence On The Coal-bed Gas Reservoir Formation In The Linfen Area

Linfen is located in the edge area of the southern Ordos, which coal-bed gasresources are very rich. The overall structure of this area is relatively simple, which isshown as tilting to NW monoclinic structure. But the structural evolution is relativelycomplicated, mainly experienced three periods of structural movement, in which theYanshanian structural movement lays a main structural framework of this area.Controlled by structure action, the structure fracture of this area is relativelydeveloped, and it certainly appears rules. The structure fracture, which formed underthe control of the structure action, has an important influence on the coal-bed gasreservoir formation.On the basis of a large number of relevant literature, detailed field geologyinvestigation and the indoor analysis test, The author do an In-depth research onstructural characteristics and the evolution of structure stress field, summarizes thedevelopment law of structure fracture in the Lin fen area, and combined with thegeological conditions of the coal-bed gas reservoir formation, the Influence on thecoal-bed gas reservoir formation of the structure fracture is explored. The followingconclusions are given.(1) Combined with the development characteristics of Fracture and fold structurein this area, the analysis of its mechanical properties and formation mechanism andthe research on the nature of fold and fracture and the combination form, Studiesshow that the study area can be divided into three structural divisions: Chinese redbudmountain and Matou mountain fault zone, Guyi and Yaoqu fault-fold belt and the westdipping monoclinic mitigate belt.(2) The joint structure in the study area is very developed, mainly with high anglejoint and vertical joint,56°and140°strike Joints are the superior joints of this area.The joint linear density is influenced by structure, lithology and thickness. Thedistribution direction of the10-30cm sandstone joint linear density contour and thesuperior joint contour nearly parallels to the extension direction of the main structuraltrace, which reflects the control action of structure. The microscopic fractures of rockin the study area are not developed, and they are mostly filled. The fractures of coalare relatively complicated, the distribution direction of fractal contour nearly parallelsto the extension direction of the main structural trace.(3) Combined with the above research results and the geological conditions of the coal-bed gas reservoir formation, the paper analyses the influence on the coal-bedgas reservoir formation of the development law of structure fracture, mainly from twoaspects of the permeability and gas-bearing properties of coal reservoir. The resultsshowed that under the action of current tectonic stress field, the developed areas of56°superior joints and macroscopic, microcosmic fracture are more benefit to theenrichment reservoir formation of coal-bed gas.