Sequence Division and Sedimentary characteristics of Shahezi formation in Northwest Xujiaweizi fault depression

Abstract

In the light of the unclear current conditions of the sequence stratigraphic framework division and sedimentary for Shahezi Formation in Northwest Xujiaweizi fault depression. Based on single well, well logging and seismic data,the stratigraphic sequences of the formatio n are confirmed with the help of Vail sequence stratigraphy theory. Based on the single well facies and source supply, the sedimentary facies types and the distribution characteristics of the Northwest of Xujiaweizi are analyzed. The studies show that Northwest Shahezi Formation can be divided into one second-class sequences and furthermore it can be classified into four third-class sequence; Fan delta sedimentary facies is developed in the west of study area, braided river delta sedimentary facies is developed in the east of study area, lacustrine facies is developed in the central sag; In the Northwest of the Shahezi formation, the area of the lake basin in the early stage of the sedimentary basin is small, and the latter is gradually enlarged, lake facies is the main one and the fan is mainly developed in the East and the West in this area.