Identification and geological response of Miki cycle in the ninth upper section of Naiman Depression
The upper section of the Jiufotang Formation in the Naiman Depression has great prospects for oil and gas resources,but the small grain size of the sedimentary rocks and the lack of identification of the interfaces of the stratigraphic sequences have constrained the advancement of oil and gas exploration and the prediction of the hydrocarbon source rocks.Taking the Nai No.17 Well in Naiman Depression as an example,the natural gamma logging data of the upper section of Jiufotang Formation were analyzed by spectrum analy-sis and filtering to carry out cyclic stratigraphy analysis.The results showed that the well-preserved Milankovitch cycle of the strata was divided into 17 fourth-order sequences,55 fifth-order sequences,and 138 sixth-order sequences by using the filtering curves of long ec-centricity,short eccentricity,and slope as reference curves for the division of fourth-order,fifth-order,and sixth-order sequences,respec-tively.The geological sedimentation was mainly controlled by the 405 ka long eccentricity cycle.Combined with the 405 ka filter curves and corresponding depths,the sedimentation rates at the top and bottom of the ninth upper section were calculated,and the sedimenta-tion rates were consistent with the sedimentary response of the stratigraphic attribute slices,verifying the scientificity of the stratigraphic sequence delineation in the study area,and also providing a reference for the study of fine-grained sequence stratigraphy and the deline-ation of high-frequency stratigraphic sequences in the area.
fine-grained sedimentupper section of Jiufotang FormationMilankovitch cyclegeological responseNaiman Depression
NETL
NSTL
万方数据
