Tertiary Tectonic And Sedimentary Evolution And Reservoir-Formation In The Western Qaidam Basin

Mangya depression, in the Western Qaidam Basin, is the main oil-production area for the Qinghai oil company. Although the exploration and development lasted for nearly five decades, the depression is hithernto far from being exploited completely in terms of the Tertiary tectonic and sedimentary history, and therefore preventing the unambiguous understanding to the formation of the reservoir and the oil distribution, and furthermore limiting the exploration and development of the oil field, hence resulting in the rise of the exploration and development cost.This thesis, on the basis of the deeper research of the Tertiary tectonic and sedimentary evolution of the depression, is mainly to discuss systematically the formation and distribution of the Tertiary oil and gas in Mangya depression, and provide service for the exploration and development.It is well known that, the Mangya depression in the Western Qaidam Basin is bounded by the Kunlun and Altun Tagh mountain, therefore determining the extraordinary complexity of the Tertiary tectonic and sedimentary evolvement and the reservoir-formation, and resulting in the complexity of the oil and gas distribution and rise of the exploration costOn the basis of detailed field survey for the Xichagou section and comprehensive study on the sedimentary facies and previous research achievements, the sedimentation, thermal and infilling history is studied precisely and in detail, and the Tertiary tectonic and sedimentary evolution is illuminated, and the Tertiary oil and gas formation and distribution, which is based on the research above, is further illuminated, and the favorable exploration zone is pointed out. Hence it is of important directive significance for the exploration and development of the Qinghai oil field.Moreover, as an important research achievement, the Tertiary lacustrian reef, which is never reported before in the large West China basin, is discovered in Mangya depression. This discovery is of important and practical significance for the oil exploration and development in the Qaidam basin.