| Through geological observation, combined with the regional tectonic setting, thestudy aims to restore stress field of paleostructure in the study area and have a deepdiscussion on structural development and evolution law of the study area. Analyse theobjective fractures’ developmental characteristics and measure parameters from theperspective of macro and micro. Besides, evaluate and study the stratum’s lithologyphysical property and mechanical property of the Permian shale in study area by theway of doing kinds of experiments.The main structure of the study area are mainly folds and faults, a basic form offold-controlled research area with the axial structure of NE～SW trending. Tectonicpattern experienced at least two of the major role of the paleostructure stress field:Indosinian’s NS compressional stress deflected due to the influence of Tan-Lu faultand now it changed into a nearly NW.A squeeze nearly SE～NW trend laid thestructural framework of study area―M‖shape, forming a NNE～SSW trending foldswhich is common in the region; Late neotectonism formed a NE～SW compressionalstress.As to scale,it was less than pre-stress field which led to study area NE~SW touplift the northern section of the track fold axis, causing axial trace plungingsouthward.Permian shale cracks in the region are structural fractures-based, sharing littlenon-tectonic fracture. Shale layers have high contents of brittle minerals which have astrong fracture making ability. Pores share a slit shape and they are belong totransitional pore type. Comprehensive judgments on the main controlling factors offractures are made through the research of its structural features, lithology, physicalcharacteristics, mechanical characteristics and characteristics of the burial as well asits main parameters. |
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