The study of sequence stratigraphy characteristics and the bottom boundary of Guantao Formation in the middle area of Bohai Bay Basin

By researching on the sequence stratigraphy based on the lithology characteristics, electrical characteristics, paleontology, seismic sequence stratigraphy and the study of areal geology, this paper is trying to obtain much deeper recognition of the Guantao Formation stratigraphy. Three kinds of tracts were recognized including LST, TST and HST. Based on basal level cycle technique, three kind of base-level cycles(SSC, MSC and LSC) were recognized in Guantao Formation. Guantao Formation was divided into two LSC and four MSC, and high resolution isochronous geologic correlation of Guantao Formation and upper Donying Formation. Interval from 2 782 m to 2 917 m of D5-1 well is upper Dongying Formation, and the top of this interval is the bottom of Guantao Formation.