Abstract:

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.

Key words: Mengnan basin group, geological condition, source-reservoir-cap rock condition, synthetic assessment