Research On Shale Formation Characteristics And Reservoir Forming Conditions Of Shale Gas In Lower Paleozoic In Chengkou County

The study district in the dissertation is located in Chengkou County,Chongqing City.The tectono-sedimentary evolution in Chongqing can be divided into three stages: Yangtze paraplatform basement formation stage(Jinning period),paraplatform evolution stage(Nanhua period-Triassic period)and intracontinental transformation period(Jurassic Period-Quaternary period).The sedimentary rocks in Chengkou outcropped from the Neoproterozoic Moon Fm to Quaternary strata(except in Devonian system,Carboniferous System,Paleogene System and Neogene System).The shale in the Shuijingtuo Fm of Lower Cambrian in Lower Paleozoic in Chengkou is taken as the object to analyze the shale formation characteristics and reservoir forming conditions,which has reference value to later exploration of shale gas in Chengkou.The tectonic units of Dabashan curvilinear structural belt are divided into north Daba obduction-nappe structure belt and south Daba composite foreland fold-thrust belt with Chengkou fault as the boundary.In this paper,the research is carried out according to different tectonic units,different tectonic styles,fold characteristics,fault and fracture characteristics.The study area has experienced many tectonic movements,forming a dense structure of near-east-west,north-west-south-east,roughly parallel,asymmetric pleats.The tectonic lines are in the northwest-south-east direction,and are overlapped by the multi-period tectonic action.The faults are intertwined with each other.The folds are damaged by faults and the folds are complex.The patterns are mainly complex folds.The faults are developed to thrust The main structural features of the urban fault are the recursive tectonic system formed by folds and faults,forming many longitudinal faults,extending northward to the main structural features in the south of the city,Is the combination of the thrust fold,the overall structural characteristics of the obvious rupture,deformation strength from the North East-South West decline weakened orderly,zonal.Shale gas has the characteristics of adsorption,has a certain resistance to damage,the urban area in the basin edge,tectonic damage is strong,uplift erosion effect,formation formation,fold structure,fracture and fracture development of shale gas accumulation Greater impact.In the period of geological history,the study area has experienced many tectonic alterations,and the fractures associated with folds are very developed.The thrusting faults in the northwest-south east direction are dominated by superstructures,which are cut and dislocated,Resulting in a large number of strata missing,and derived a series of secondary fault structure,resulting in gas and the top and bottom of the floor for the fault contact,the shale gas storage has a greater damage.The data of organic matter,organic matter maturity and organic matter characteristics of organic shale were analyzed by high-resolution electron microscopy scanning image analysis,microstructure and mineral composition identification.The characteristics of organic matter type,Paleozoic shale tectonic structure and analysis of shale gas accumulation conditions.