High frequency sequence stratigraphy analysis for Dawangbei subsag based on the spectrum analysis of the logging curve

Dawangbei subsag is located in the north of Chezhen Sag. Deep-water nearshore subaqueous fan and fan delta are mainly developed in the northern steep slope in the member 3 of Shahejie Formation (ES3). With greatly complex sedimentary structure and no obvious mudstone interlayer, the stratigraphic division and correlation of glutenite reservoir in this area is difficult to be correlated and tracked. Aiming at this problem, this paper analyzes the logging data, clarifies the characteristics of sequence interface, introduces the theory of climate cycle driven by astronomical cycle in astronomy stratigraphy, studies the sedimentary formation conditions of glutenite, and identifies and compares the cycle interface of glutenite. The analysis results show that the stratigraphic cycles in the study area are mainly controlled by the long orbital eccentricity cycles of 400ka and the short orbital eccentricity cycles of 96ka. The thickness of the cycles is controlled by the long orbital eccentricity cycles and the short orbital eccentricity cycles ranging from 113.55 to 197.82m and 26.93 to 48m, respectively. The logging curves are filtered by the information of dominant cycle frequency. According to the filtering curve, the sequence is divided into different orders of sequence. After determining the partition scheme, ES3 is divided into 3 third-order sequences, 6 fourth-order sequences, and 28 fifth-order sequences, which builds the well correlation section and correlation framework of stratigraphic cycle from the provenance direction to the sag center.