The Tectonic Characteristics And Its Control Over Oil And Gas In The Yu Qia-Hong Shan Fault Depression Of The North Margin Of The Qaidam Basin

The Yu Qia-Hong Shan fault depression of the North Margin of the Qaidam Basin includes Yu Qia fault depression, Qaidan-Hong Shan fault depression and Hong Shan tectonic belt, which locates in the eastern section at the north margin of Qaidam Basin. Because the influence of multistage tectonization, the structural traps were serious destroyed, which was hard to explore, however hydrocarbon source rock developed in research area, and the oil sands were over there, the better fluid of oil and gas was found by using shallow well drilling. So, according to study on the tectonic characteristics and its control to oil and gas in the Yu Qia -Hong Shan fault depression at the North Margin of Qaidam Basin, oil and gas exploration is not only better deployed and developed, it is also significant to research on the whole area of North Margin of Qaidam Basin.After brief anglicizing regional tectonic evolutions of study area, compilated backbone seismic section interpretation maps, structure outline maps and geologic section maps, summarized fold structures and fault structures'basic characteristics, plane distribution regularity and section assemble pattern of Yu Qia- Hong Shan fault depression. Summarized that synclines are open, anticlines are tightly closed, and plane distribution pattern of folds was parallel and juxtaposition. The faults were mostly thrust fault, and tectonic types can be divided into 3 styles: compression tectonic style, strike-slip style and extending tectonic style. Based on analysis of formation angular unconformity methods, it studied regional structural deformation stage. And also analyzed area structure through tectonic evolution sections' compilations. Analyzed tectonics' controls over hydrocarbon source rock development and distribution, types and characteristics of tectonic trap, and the tectonic characteristics' control to hydrocarbon migration and accumulation. Considered that the tectonic had important control to hydrocarbon source rock development and distribution. There are many anticlines, faulted anticlines and fault block tectonic traps. The result of tectonic control is that oil and gas mainly run with lateral migration firstly. It significantly run with vertical migration latter, faults are important pathway to vertical migration. After analysis and research, the main six factors are got, which are oil source condition, reservoir conditions, cap rock condition, trap conditions, migration and accumulation condition, preservation conditions. According to above six factors, Yu Qia fault depression is the I favorable exploration researched belt, Qaidan-Hong Shan fault depression is the II favorable exploration researched belt and Hong Shan tectonic belt is the III favorable exploration researched belt.