Efeect Of Kuche Tectonic Evolution For Hydrocarbon Accumulation

Of all the four factors which influence the basin, tectonic movement is the most important one. It not only decides the Stratal framework and tectonic framework, but also impacts the distribution of hydrocarbon source rock and reservoir and the thermal evolution process of the hydrocarbon source rock. Moreover, it exerts the significant effect on migration, accumulation, and preservation of oil gas. This paper first studies the tectonic movement, and then from the perspective of it explains the conditions of generation and accumulation of oil gas in kuche depression.The author put emphasis on the structural evolution history which developed after Triassic. After analyzing data of kuche depression, the author chose some typical profiles and resumed tectonic evolution history of kuche area relying on balanced section theory and using GEOSEC software. Tectonic movement is fewer from Triassic to early Cretaceous, but in the late period of Cretaceous the tectonic movement had become stronger and a large-scale tectonic uplift denudation formed. As a result, there is only sediment in Lower Cretaceous in sedimentary formation without the sediments in Middle and Late Cretaceous. At the same time, three exploratory wells and two simulating wells were chosen to study on the burial history and thermal history of this area. According to the information gathered from burial history, the strongest tectonic movement in Kuche depression happened 5Ma ago. Later under the persistent press force, stratum sank fast so as to absorb sediment, and after the sediment reached several kilometers, the tectonic inversion happened. Therefore, the stratum turned to be the tectonic uplift from the tectonic subsidence, and the exposed earth's surface suffered from denudation whose thickness reached 2 kilometers. The analysis of thermal history also verified the impact of tectonic uplift. After tectonic evolution, the burial history and thermal history were analyzed comprehensively, the conclusion can be reached that the stratum denudation in middle and later Cretaceous and strong tectonic movement in Miocene Period are matched in three former mentioned histories.