敦煌盆地演化特征及致密油勘探方向

Evolution Characteristics and Tight Oil Exploration Direction of Tight Oil in Dunhuang Basin

侏罗系是敦煌盆地重要的勘探层系,侏罗纪盆地的性质、发育演化及其油气潜力一直是人们关注的热点。在充分消化前期研究成果的基础上,依据盆山一体化的研究思路,分析了盆山的耦合关系,研究了盆地性质、发育特征及演化过程。研究发现,三危山在三叠纪末期已经隆升,同北山、阿尔金山共同控制了敦煌盆地侏罗纪时期的沉积充填;早、中侏罗世盆地具有明显的断陷性质,是烃源岩发育的主要时期,差异升降形成多个小型湖盆,各湖盆独立分布,分割性较强;晚白垩世至古近纪时期,盆地经历反转改造作用,导致白垩系剥蚀殆尽,上侏罗统部分剥蚀,以晚燕山期走滑隆升和喜马拉雅期走滑逆冲为主要改造特征,对烃源岩的演化过程、油气的聚散等均有重要影响。

Jurassic is an important exploration layer in Dunhuang Basin,and its nature,evolution and hydrocarbon potential of Jurassic Basin have always been the focus of attention.Based on the results of previous studies,and using the basin-orogen integration ideas,it is proposed that the Sanwei Mountain is uplifted at the end of the Triassic and jointly controlls the sedimentary filling in Jurassic period of Dunhuang Basin with Beishan and Altun Mountains.The early and middle Jurassic basins are characterized by obvious fault depression,which is the main period for the development of source rocks,various small lake basins are formed by differential uplift and subsidence,each lake basin is distributed independently and has a strong division.During the Late Cretaceous to Paleogene,the basin experiences reverse transformation,resulting in the erosion of Cretaceous and partial denudation of Upper Jurassic,with strike slip-uplift in late Yanshanian Period and Himalayan strike slip-thrust as the main types.The characteristics of transformation have important influence on the evolution process of hydrocarbon source rocks and the accumulation of oil and gas.