China Petroleum Exploration ›› 2010, Vol. 15 ›› Issue (4): 19-25,8.

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Unconformity Characteristics ofWest Segment of NorthernMargin in QaidamBasin and Its Significance in PetroleumExploration

Wang Zhaoming,Luo Xiaorong,Wang Liqun,Ma Lixie,Shen Yushen,Gao Xuefeng and Li Yeping   

  1. Wang Zhaoming1,Luo Xiaorong2,Wang Liqun3,Ma Lixie3,Shen Yushen3,Gao Xuefeng3,Li Yeping3//1.Research Institute of Petroleum Exploration& Development,PetroChina,Beijing 100083;2.Institute of Geology and Geophysics of Chinese Academy of Science,Beijing 100029;3.Exploration and Development Research Center,PetroChina Qinghai Oilfield Company,Dunhuang City,Gansu Province 736202
  • Online:2010-08-15 Published:2010-08-15

Abstract: Unconformity plays an important role in petroleum accumulation. It could be a kind of conductor for lateral petroleum migration and could also obstruct petroleum migration to form unconformity reservoirs. This paper analyzes the unconformity between Mesozoic and Cenozoic of west segment of northern margin in Qaidam Basin from the aspects of stratigraphic contact relationship, lithologic allocation relationship, basal conglomerate distribution and thickness, identifying seven kinds of stratigraphic contact relationship and five types of lithologic allocation relationship, and analyzing the effect of different allocation relationship on petroleum accumulation. It summarizes the role of unconformity in petroleum accumulation. First of all, unconformity is the most important lateral and longdistance conductor from source to reservoir. Secondly, existence and formation of unconformity directly affects the petroleum accumulation and distribution. According to the characteristics of unconformity development, considering other accumulation conditions, this paper puts forward that the buried area and Lenghu No.7 area of Saishiteng sag are favorable for exploration

Key words: unconformity, stratigraphic contact relationship, lithologic allocation relationship, basal conglomerate, petroleum accumulation, lateral migration, Qaidam Basin

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