Abstract:

Renqiu buried hill oilfield is one of the big oil fields with high productivity in China even in the world.The buried hill trap is 30 km² in north-south,7 km² in east west with an area of 183 km².The reservoirs are carbonate rocks of Lower Palaeozoic,Middle and Upper Proterozoic,the source rocks are pelite of Es₃₊₂ ,the caprocks are mudstone and halite of Es 1+Ed.The major oil pools,resulted from NWW striking Tongkou transformation belt and NNE striking Renqiu uplift,are in Middle Proterozoic carbonate rocks in the northern part of the buried-hill.In Es₃₊₂ depositional period,the transformation belt displaced northward to Mo-14 ～Mo-2 Wells neighborhood.Then Renqiu uplift subsided under the water and became the buried hill.Lingcheng subsag in Baxian sag and Renxi subsag in Raoyang sag which are situated in two sides of the buried-hill provided rich hydrocarbon source and mingling crude oil for Renqiu Oilfield.In Es₁～Ed period,the transformation belt moved north to Gaojiapu area,resulted in the recession of the two subsags,and formed regional mudstone caprock.In Ed～N period,source rocks matured and formed Renqiu oilfield of buried-hill trap type.

Key words: Renqiu, big Oilfield, transformation belt, Jizhong Depression