The Sequence Stratigraphy And Depositional Systems Of Member 1～4 Of Shahejie Formation Of The Eogene In Maozhou Area Of Baxian Depression

The Member 1～4 of Shahejie Formation is the major exploration interval of Maozhou area in Baxian depression. As the exploratory objects are gradually focused on the lithologic or stratigraphic reservoirs, more accurate research to types of sedimentary facies and depositional system distribution are needed urgently. Using plentiful geological and geophysical data, and based on the fundamental principles of sequence stratigraphy, the isochronal framework of sequence stratigraphy were established. Based on the identification of facies markers in core,log,seismic and palaeontologic,the depositional system distribution and control factors in isochronal frame of sequence stratigraphy were discussed. With the studying of reservoir forming condition,the distribution law of sandbodies and hydrocarbon were analysed,and pool-forming model was summarized. As a result, the favourable goals were pointed out.Based on the division of sequence stratigraphic boundary, all the sequences and their boundaries of the Member 1～4 of Shahejie Formation were decentralized. The Palaeogene can be subdivided into 7 3rd-order sequences with 21 4th-order sequences. The upper submember and the lower submember of Member 4 were divided firstly. Through sequence stratigraphic subdivision and correlation of key wells and seismic sections,the sequence stratigraphic framework and sedimentary system models were established.Integrated core facies, log facies,and seismic facies etc, five types of sandstones including delta, tempestite, nearshore subaqueous fan, fan delta, and turbidite have been identified. The tempestite and turbidite were the firstly discovery in the area, which enriched the sandstones types and enhanced the exploration potentiality.By studying depositional system in isochronal frame of sequence stratigraphy, the distribution rules of sedimentary facies were studied in detail. Another reaseach showed that the source-reservoir-seal associations in this area was very favourable. The control factors of sandbodies and hydrocarbon distribution have been also studied, and the resulst showed that the sandbody types were controlled by systems tracts, the highstand systems tract and the lowstand systems tract are rich in sand, while transgressive systems tract is poor in sand. The plan distribution was controlled by the tectonic, palaeotopography, provenance and climate.According to the analysis of depositional system distribution and reservoir forming condition, hydrocarbon accumulation models were summarized. At last, the favorable districts were pointed out and the direction to search for different types of reservoir was given.