蒙南盆地群石油地质条件评价

ASSESSMENT ON GEOLOGICAL CONDITION OF PETROLUM IN MENGNAN BASIN GROUP

蒙南盆地群位于内蒙古中西部 ,由大小不等的 10多个盆地组成。与油气有关的沉积地层主要是侏罗系和白垩系。经野外露头剖面和钻井岩性分析 ,下、中侏罗统五当沟组、厂汉沟组和下白垩统固阳组发育深湖半深湖相泥 (页 )岩、碳质泥岩和泥灰岩 ,是区内主要的烃源岩。烃源岩已进入成熟阶段 ,处于生油高峰期。侏罗系白垩系发育多套扇三角洲、分流河道以及三角洲前缘砂体 ,是较好的储集砂体。其中 ,侏罗系储集砂体的孔渗条件较差 ,白垩系砂体的孔渗条件较好。从整体上看 ,侏罗白垩系不仅具有下生、中储、上盖的组合型式 ,而且各层序亦具有自生、自储、自盖的组合型式。综合分析后 ,认为武川、桑根达来盆地为勘探最有利地区 ,三道沟、旗下营、乌兰花。

Mengnan basin group is situated in the midwest of Inner Mongolia.The group consists of more than 10 Mesozoic basins.The main source rocks are Wudanggou and Changhangou Formations of Middle Lower Jurassic,the Lower Cretaceous Guyang Formation.The sediments are mudstone,shale,carbonaceous mudstone and marl of deep and semi deep lake facies.The source rocks are matured and in the peak stage of oil generation.Multi set of fan delta,distributary channel and delta front sand bodies of Jurassic and Cretaceous are favorible reservoirs.On the whole,the Jurassic Cretaceous Systems possess not only the combination of oilsource rocks in the lower part,reservoirs in the middle part and cap rocks in the upper part,but also the combination of self generation,self-reservoiring and self coverage.It is considered that Wuchuan and Sanggendalai Basins are most favourable for oil exploration;Sandaogou,Qixiaying,Wulanhua and Guyang Basins are secondary.