The Sequence Stratigraphy And Petroleum Geology In Chezhen Depression

Chezhen sag, a sub-depression of the Jiyang depression, is located at the north of the Jiyang depression, which belongs to the Bohaiwan basin. Based on the materials of seismic exploration, well-logging, drilling core and paleontology etc., the Es3-Ed of the Chezhen sag has been divided into 2 2nd-order sequences and 6 3rd-order sequences. And on this base, the geological factors which control the development of the sequences and the formation mechanism of sedimentary sequences have been discussed. The sequence models include 3 types, they are escarpment pattern, flat ramp pattern and depression pattern. The sedimentary system has been studied in detail. It has been considered that the Chezhen sag has developed 8 kinds of facies. The evaluation rules and distribution features have been analyzed. Based on the study of the geological and geochemical characters of the source rock, the source comparison considered that the oil in the Yihezhuang relief and its north part is partly from Guojuzi sag, Dawangbei sag, Chexi sag and Sikou sag. Oil in the Yihezhuang buried hill comes from Es3 source in the Sikou sag mainly. The oil in the Guojuzi area comes from Es3 source in the Guojuzi sag. The oil in Dawangzhang mainly comes from the Es3 and Es1 source in the Dawangbei sag. Based on the analysis of the reservoir types, the formation mechanism of the reservoir in different period has been discussed. And the lithological reservoir has been studied as a important part. At last, the relationship among the sequence, sedimentary system and oil distribution has been analyzed.