Study On The Distribution Characteristics Of Carboniferous-Permian In Santanghu Basin

Santanghu basin is small and rich in hydrocarbon resources,which is located in the northeast of Xinjiang.With the continuous exploration of the basin along the Mesozoic to Upper Paleozoic,the great breakthrough of oil and gas were found in the Carboniferous-Permian of Niujuanhu in 2006,since then,the exploration of the Upper Paleozoic in the Santanghu basin has started.According to the available data,in recent years the study of the Carboniferous-Permian in the Santanghu basin is concentrated on the Malang sag,which is lack of holistic and comprehensive research,especially by the use of geophysical methods.Usually,in addition to drilling data,geophysical exploration is one of the best methods to reveal stratigraphic distribution and depth.Thesis combined with the predecessors' research results and geophysical data to comprehensively study on the distribution characteristics of the Carboniferous-Permian in Santanghu basin.In this thesis,using the existing gravity and magnetic data in the Santanghu basin,through various methods processed the gravity and magnetic data,combined with drilling and seismic interpretation and regional geological research results,systematically analyzed the characteristics and causes of gravity and magnetic anomaly in this region.According to different parameters of gravity and magnetic conversion parameters reconstructed and explained fracture system and analyzed the control of fracture on the upper Paleozoic.Then,using the 2.5D gravity positive and inversion simulation software simulated the main section,based the results divided the tectonic units,and analyzed the depth and thickness characteristics of Carboniferous-Permian in different tectonic units.Finally,according to the previous research results,using the method of “joint inversion of gravity data under the constraints of seismic and drilling data” to inverted the interface of the Carboniferous-Permian in Santanghu basin,and analyzed the depth of top and bottom interfaces and thickness characteristics,besides,predicted the favorable area of oil and gas.The paper has the following main results and conclusions:(1)The anomalies of Bougur gravity in Santanghu basin is distributed a“high-low-high” pattern,two high-gravity anomalies are on the southwest and northeast,alow-gravity anomaly is in the center.The high and low gravity in the area reflects the tectonic pattern of basement uplift and depression.The pattern of residual gravity anomaly is obvious,which basically reflects the depression and uplift pattern of the basin.Residual magnetic anomalies are well developed in the basin,suggesting that the volcanic rocks in the basin developed.(2)The Santanghu basin is tectonic complex and fault development.Main faults in NW?NE and EW trending,the NW formed initial stage of the basin evolution and extended from the Carboniferous strata to the surface,play an important role in control the distribution of the Upper Paleozoic.The NE trending faults are formed in the middle and late stages of basin tectonic evolution,they are mainly distributed in the central depression zone and controlled Secondary structural unit.(3)According to the residual gravity anomalies and fault systems,Santanghu basin can be divided into three first-order tectonic units,including the southwest thrust and nappe uplift,the central geotectogence,and the northeast thrust and nappe uplift.The center geotectogence is divided into eight sub-tectonic units from northwast to southeast.(4)The Carboniferous-Permian in the basin is widely distributed and has a large thickness.The depth of Carboniferous-Permian bottom interface change obviously,and gradually rising from north to south,they are buried deep within the four depressions and gradually rise from the middle to the periphery.The thickness varies laterally,the center of the depression is thicker,and gradually decreases toward the periphery.(5)The upper Paleozoic in the Santanghu basin has good petroleum geology and reservoir forming conditions,has a great prospect of oil and gas exploration.Malang and Tiaohu sag had explored,next should be Hanshuiquan and Naomaohu sag,then is southwest thrust and nappe uplift.