| The southern thrust belt of Junggar basin is an important part of the oil and gas exploration in the midwest of China's foreland basin, it's also a hot and difficult part of exploration in recent years. In 2011, it is considered that Dushanzi anticline and Hutubi anticline are favorable structure by studying the implementation of the overall structure and comprehensive evaluation and optimization of petroleum geological conditions, the well Dushanl and Dafengl reveals the Jurassic reservoir of large-scale development, but as a result of the degree of the implementation of the structure is relatively low, the causes of structure is unknown, and the rationality of the tectonic style, the two wells failed to obtain a breakthrough, brings great difficulty for further exploration.This research is to establish typical models of Huoerguos anticline, Manas anticline and Tugulu anticline, by use of the theory of structural geology and the theory of fold related to fault. And verified the rationality of the three model by balanced cross-section, modeling analysis, and tectonic evolution analysis. Then conducted structure interpretation combined 2&3D seismic data to carry out the structure development characteristics, and made the following points:(1) The southern thrust belt of Junggar basin mainly experienced three periods of tectonic evolution stages since Carboniferous:Intracontinental rift evolution stage of Carboniferous-Permian, intracontinental basin evolution stage of the late Triassic-Miocene epoch, foreland basin evolutionary stages of Pliocene quaternary. The structure of nowadays is mainly controlled by himalayan tectonic movement, structure began to form in Shawan group (N\s) sedimentary period, intensified in Dushanzi group(N2d) sedimentary period, and has the characteristics of "south earlier, north latert" in general.(2) The following understanding is obtained by structure modeling and geometry analysis:The Huoerguos anticline, Manas anticline and Tugulu anticline are controlled by three sets of plastic layer:coal of the Jurassic, lacustrine facies mudstone of the cretaceous, and lacustrine facies mudstone of Anjihaihe group. They all have tectonic style of "triple structure", that means it is fault-bend fold in the deep, tectonic wedge in the middle and fault propagation folds in shallow, and this three sets of structural layer formed in turn from down to up.(3) The tectonic deformation simulation and tectonic evolution results of Huomatu structure by 3D Move show the following:Limitations of intracontinental rift may be developed in Jurassic in the south of the Huomatu anticline, it has a certain control function for the formation of the late.(4) Structure interpretation results show the following:The Huoerguos anticline, Manas anticline and Tugulu anticline arrangement for the triangle in the plane. There are a row of structure like Anjihai anticline in the north of Manas anticline and Tugulu anticline, but its scale is smaller than Anjihai anticline.(5) Controlled by different types of fold in the longitudinal, there are rolling, complete, large area of anticline structure mainly develop in lower tectonic layer; And narrow, relatively complete anticline structure mainly develop in middle tectonic layer, but secondary fracture develop in the anticline subject; The upper tectonic layer is controlled by the strongly nappe of late himalayan intense, this leads to the fracture development in mudstone of Anjihaihe group break through the earth's surface, so the structural of the upper tectonic layer is broken seriously, it is mainly monoclinal structure in the hanging wall of the fault, and it is mainly high and steep broken nose structure in the footwall of the fault, and the preservation conditions is poor. |
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