Analysis Method and Indicator Optimization of Astronomical Cycles in Lacustrine Fine-Grained Sedimentary Strata- A case study of Es4scs in Well Niuye 1, Dongying Sag, Jiyang Depression, Bohai Bay Basin

In recent years, great progress has been made in fine-grain sedimentary oil and gas exploration. However, the rotary division of fine grain sedimentary strata is an important foundation of fine grain deposition oil and gas exploration. With the development of research, the complexity and differences of indicators and methods in the rotary division have led to the increasing contradiction of research results. The lacustrine shale from the upper interval of the upper sub-member of the 4th member of the Paleogene Shahejie Formation（Es ₄ ^scs ）in Well Niuye 1，Dongying Sag，Jiyang Depression，Bohai Bay Basin was used as the study object. This study was conducted by combining testing methods and techniques such as X-ray diffraction whole-rock analysis, X-ray fluorescence spectroscopy, TOC analysis, and magnetic susceptibility testing. Based on the data of geophysical, geochemical, environmental magnetic parameters magnetic susceptibility, mineral content and core grayscale, and using TSAM 1 and TSAM 2 methods to optimize the rotary analysis method and sedimentation series substitution indexes. The research results are shown as follows. First, The TSAM 2 method has the best results for GR, AC, RL, RN, log series principal component analysis and log series factor analysis. Second, The TSAM 2 method works the best for the magnetic susceptibility data. Third, TSAM 2 was best for Fe, Mn, Ti, Ca, Al, Si, CaO / MgO, (CaO + K ₂ O + Na ₂ O) / MgO Al ₂ O ₃ , (Fe + Al) / (Ca + Mg), principal component analysis and factor analysis of each element data. Fourth, In the core grayscale data, the TSAM 2 method has the best effect. The data identifies smaller solar cycles than the transition cycle scale. Fifth, The optimal deposited sequence substitutability index is the natural gamma logging data, and the optimal time series analysis method is TSAM 1. Sixth, The study strata identified 5 long eccentricity cycle of 405 kyr , 22 short eccentricity cycle of 95.24kyr , 48 obliquity cycle of 39.76kyr, 53 obliquity cycle of 38.54kyr , 87 precession cycle of 23.28kyr, 98 precession cycle of 22kyr and 107 precession cycle of 18.82kyr. The study concluded that the deposition time was roughly 2.038Ma, and the average deposition rate is estimated to be 0.074m / kyr. This research is helpful to promote the research of scientific problems such as the establishment of rotary geological age and the determination of terrestrial rotation level. Meanwhile, it has a good application value and research prospect for the development of fine-grain sedimentary spiral stratigraphy.