Structural Features And Its Effect On Hydrocarbon Accumulation Of Tugerming Anticline In The Eastern Kuqa Depression

The Tugerming anticline in the eastern Kuqa depression has experienced multiple periods of tectonic deformation and fault activity,and the distribution of oil,gas and water is complex.The rationality of structural analysis directly affects the understanding of structural kinematics process,dynamic mechanism and hydrocarbon accumulation in the study area.Based on the field observation data,drilling and seismic data,this thesis uses the principle of triangular shear fault propagation fold to interpret the seismic reflection blank area,and uses the balanced section restoration principle to recover the structural evolution of Tugerming area in the eastern Kuqa depression.On this basis,the tectonic control of reservoirs is discussed and the favorable exploration direction is pointed out.The results are as follows:(1)Separated by Tuziluoke fault and Tugerming fault,the structural style of the study area can be divided into the deeply buried forelimb,the kink band and the tiny anticline backlimb,the tiny anticline backlimb can be subdivided into Tugerming anticline segment and northern deep buried segment.The Tuziluoke fault has been active since the sedimentary period of the Kuqa Formation and maintained a strong activity intensity,which controls the formation of the huge thick growth strata in the deep buried forelimb and the present Tuziluoke anticline.The Tugerming fault has been active intermittently since the end of the Jurassic,causing the denudation of the J₃-E strata to varying degrees in local areas,and series of regulating faults have developed around it.Temporally,the fault activity was strong before the deposition of Cretaceous and Xiyu Formation,and the maximum shortening rates of the profiles were 3.74%and 13.85%,respectively.Spatially,the activity in the central and western part of the working area is the strongest,and the activity in the eastern part is weak.The upper part of the ancient structure is controlled by the Tugerming fault(F2),while the present high part of the structure is produced by the superposition of the large anticline generated by the Tuziluoke fault(F1)and the backlimb Tugerming anticline.The multi-stage tectonic movement caused the structural high of the anticline migrates from east to west along the strike.(2)Structural activities in Tugerming area control the burial evolution process of different zones,reservoir physical properties and cap rock preservation conditions obviously.The anticlinal core area presents early medium burial and late strong uplift with present shallow burial depth.The reservoir is characterized by high porosity and high permeability,but the source rocks are immature,and there is a lot of denudation in the anticlinal core,and the oil and gas leak along the denudation skylight,and the preservation conditions of the oil and gas are poor.The northern limb slope shows early deep burial and late weak uplift,and the source rocks are mature,but there is no local structural high point and the reservoir physical property is very poor.In the eastern part of the anticline,the local tectonic high part presents early,medium buried and late weak uplift.The source rocks are mature and the reservoir physical properties are relatively good.Therefore,the local structural high in the eastern part of the anticline with deep burial is the favorable area for oil and gas accumulation.The southern depression shows the evolution characteristics of early medium burial and later fast deep burial,and is close to the main hydrocarbon generation center of Yangxia depression.The reservoirs are mainly thin-bedded delta front sand bodies with relatively good physical properties.(3)Tugerming area has a two-stage charging process of early oil and late gas and a process of late adjustment and finalization,and the late mature natural gas mainly comes from the deep depression area of the footwall fault.The favorable exploration directions of Jurassic Tugerming mainly include:the local structural high on the background of anticlinal slope,the structure-lithological trap in the lower part of the south and north slope of anticline,and the deep structure-lithological trap in the footwall of fault.