Restoration Of The Prototype Basin Of Late Cretaceous In Subei Basin

After more than thirty years oil and gas exploration in Subei Basin, the main oil and gas discovery and the main exploration is centrated on Tertiary system's lithology. Along with the continuous in-depth exploration, the oil and gas exploration degree of Tertiary system also has been enhanced and the difficulty of exploration is from more to more great. We have to enter fine exploration and deep-seated exploration . The main direction of next exploration in Subei Basin is new target of oil and gas exploration area.Taizhou formation of upper Cretaceous is a new target of oil and gas exploration in Subei basin. In past few years, the reservoirs of Taizhou formation found in Haian Sag. and Gaoyou Sag. show a positive exploration potential. The further study on the prototype basin which controlled the formation of the reservoirs of Taizhou formation is necessary. Based on the study of regional seismic profile and the distribution of conglomerate, original deposit boundary of basin is confirmed; also based on the study of the distribution of heavy minerals, the change of the thickness of the sandstone or mudstone and connected profiles of wells, then the source of sediments of that time is confirmed; and based on the combination of seismic facies and single-well facies can restore sedimentary facies of that time, further restore the prototype basin of late Cretaceous in Subei Basin. Prototype basin in the sediment period of Taizhou formation was that when 1st member of Taizhou formation was deposited, Subei basin was divided into Dongtai Depression and Yanfu Depression by Jianhu uplift. While in the two depressions, salient controlled the thickness of deposition, the material mainly came from Tongyang uplift, Lusu uplift and Jianhu uplift; When 2nd member of Taizhou formation was deposited, Subei basin was an integrated basin. In east of basin was deposited in lake facies, while in west of basin was deposited in fluvial facies and flood plain facies. During the stage, the material mainly came from Tongyang uplift and Jianhu uplift, while the amount is relative small.At the same time, After integrate research,we think that sanduo's movement had main imfluence about evaluate on taizhou's formation。Through combine well and seismic, restore stratigraphic denudation amount and further restore the depth of Taizhou formation of different geologic period. Through analyse representative district seismic profile's tectonic evolution, think that the main tectonic visage didn't take place great change although through time after time tectonic movement.