Characteristics Of Deformation And Evolution Of Fault Structure In The Eastern Bachu Uplift

The Bachu uplift is located in the western part of the central uplift of the Tarim Basin.The formation of oil and gas traps is closely related to the faults.At present,the study on the identification and evolution of the eastern boundary faults and three-dimensional faults is still weak,and further research is needed.Based on the newly acquired 3D seismic data and 2D and drilling data in recent years,this paper studies the theory of oilfield structure and analyzes the seismic section and the structural mapping of the eastern part of Bachu uplift.The geometric and kinematic characteristics of the faults in the eastern of the Bachu uplift and the faults in the west and the east of the 3-D area of Hetianhe.There are many different types of fault zones and fault-related fold structures in the eastern part of Bachu uplift.The NW and NWW thrust fault zones that control the main deformation of Bachu uplift mainly include the Tumuxiuke basement-involved compression-torsion tectonic belt,Kalashayi basement-involved compression-torsion tectonic belt,Mazhatage composite structural belt(shallow detachment fault developed in the Paleogene,becoming a vertical superposition structure style with the lower basement-involved fault),Gudongshan composite structural belt(shallow detachment fault developed in the Middle Cambrian,becoming a vertical superposition structure style with the lower basement-involved fault).The west of the 3-D area of Hetianhe mainly develops the NE-trending Hetianhe-5 thrust fault zone and strike-slip fault zone along the Middle Cambrian gypsum slip;the east of the 3-D area of Hetianhe develops a near-EW strike high-angle fault zone and has strike-slip characteristics.The NE is going to break.The NE-trending small fault zone distributed between the main fault zones is basically broken down into the Middle and Lower Cambrian and the basement,and is broken up to the T46 interface to the Quaternary strata.There are deep basement faults or reverse faults in the lower part;there are mainly two types of profiles in the upper part: folds or single high-steep vertical faults.The fault tectonic evolution of the eastern part of Bachu uplift is divided into five stages through fault tectonic deformation,fault evolution and compiling a balanced profile: the early Caledonian period,the middle-III Caledonian period,the late Caledonian–early Hercynian period,the late Hercynian-Indosinian period and the middle and late Himalayan period.Activity of the structural belt in the middle Caledonian period controls the development of sedimentary facies belt;karstification and fault activity control the development of the Lower Ordovician fractured cave reservoir;multi-stage fault activity controls trap formation and hydrocarbon migration and accumulation.