The Tectonic Characteristics And The Evolutional Regularity Of Han Wangchang In Western Sichuan Foreland Basin

Western Sichuan foreland basin is always a hot spot for oil and gas exploration. For decades, many well-known geologists have carried out detailed study on the western Sichuan Basin, and given lots of important insights. All these effectively guide the oil and gas exploration in the western Sichuan Basin. But the drilling facts on Mingshan and Han wangchang areas in the southern basin in the past more than ten years indicate that the actual structure of underground is very different from the existing understanding. Therefore, to reknow the underground structure of Han wangchang is very exigent.Han wangchang is located in the southwestern part of low and steep structural area in western Sichuan depression , and it is the joint of Long quanshan-Xiongpo structural group and San hechang structural group. From previous studies, the ground structure of Han wangchang is a nose-like structure in the southern section of Xiongpo anticline, which is quite different from that of the hinterland .In the hinterland, the structural framework from shallow to deep is basically similar, and faults develop. This paper that uses the structural geology of petroleum as an entry point analyze the structural style and tectonic evolution from the structure of the kinematics, geometry and dynamics and other factors.The research mainly proceeds the interpretation of the seismic profiles, draws up the structural maps of the main reflecting surfaces and meanwhile preliminarily analyze the geometric characteristics of Han wangchang structure by establishing the Isochronous structural and stratigraphic framework of Han wangchang buried structure ;emphasizely analyzes the profile evolution of Han wangchang , obtains the cognition of structural geology thay complys with the actual characteristic of regional structural deformation and lays a solid foundation for the strategic oil and gas exploration for the next step. Through this research, the main works and understandings are as follows: 1, establish the the Isochronous structural and stratigraphic framework and the structural geological pattern by the guide of structural stratagraphic theory and research methods.2, Through the analysis of the seismic profiles, it is supposed that the structural styles contain fault-related folds and inverted structures. And the fault-related folds include simple bending structural style,fault-bend folds,back thrust uplift and so on. And there are two completely different tectonic styles developing to the interface of the Lower Triassic gypsum-rich layer. Rows of parallel and diagonal fault-related folds develop above the gypsum-rich layer as the bottom detachment, and inverted structures develop below it.3, Seen from the structural distribution characteristics, the ground structure of Hanwangchang is a nose-like structure in the southern section of Xiongpo anticline, which is quite different from that of the hinterland .In the hinterland, the structural framework from shallow to deep consistently is a anticline and basically similar, and faults develop. The structural difference between the shallow and the deep is that the structural high spots have changed affected by the impact of faults.4, Seen from the fault plane distribution, we find out that the faults in this region is parallel to the tectonic axis. According to the trends of the faults, the fault system can be divided into three groups, namely, N E,N-N-E and N-S to N-E. N-S trending faults are mainly distributed in the southern and middle parts of this study area; N-N-E trending faults are mainly distributed near Wanshan in the southern part of this study area; N-S to N-E trending faults are mainly distributed in the northern study area, and mainly develop in the shallow. From the structural map, there are more upper faults and less lower faults in the number, which indicates that the study area went through a regional tectonic movement. in the late.5, By the utilization of balanced cross-section technology to produce evolution history for four balanced cross-section profile, by analyzing the evolution history and synthesizing the views of the predecessors, the tectonic evolution of the study area can be divided into two phases: the Paleozoic passive continental margin development stage before the end of the Middle Triassic and the foreland basin development stage from late Triassic to Present. The key tectonic movements that effect this study area contain: early Indo movement, Anxian movement, late Indo movement, Yanshan movement, Himalayan movement. Especially Anxian movement and Himalayan movement based.Indo early movement, County movement, Indo-late movement, Yanshan movement, Himalayan movement. County sports and especially Himalayan movement based.