米氏旋回在涠西南凹陷WZ11-4N油田高频层序地层识别与对比中的应用

针对应用常规方法进行高频层序划分和对比容易受人为因素影响,所建立的高级别层序地层格架具有多解性等问题,本文引入天文地层学中气候旋回受天文周期驱动的理论,选择涠西南凹陷WZ11-4N油田4口钻井中的流一段地层为研究对象,进行米兰科维奇旋回特征分析。对自然伽马数据进行频谱分析的结果显示,在不同钻井中,流一段地层主要受偏心率周期(401ka、125 ka和95 ka)控制。对该周期滤波分析后,选择控制流一段发育的主要米兰科维奇周期曲线,建立了该区的高分辨率天文年代标尺。最后以偏心率125 ka周期曲线作为6级层序划分的参考曲线,对流一段层序进行高频旋回地层划分与对比。在此基础上,最终实现高频地层格架下沉积相的精细对比。

High-frequency sequence stratigraphic division and correlation for the WZ11-4N Oil Field in the Weixinan depression by using the Milankovitch theory

The strata in the 1st member of the Liushagang Formation are explored with the aid of the Milankovitch theory for the selected wells of the WZ11-4N Oil Field in the Weixinan depression. The spectral analysis of the natural gamma-ray spectral logs shows that the strata in the 1st member strata of the Liushagang Formation are dominantly controlled by the 401 ka, 125 ka and 95 ka eccentricity cycles. The high-resolution astronomical timescale is based on the major Milankovitch curves for the 1st member of the Liushagang Formation. The 125 ka eccentricity curves are used as the referenced curves for the 6th-order sequence stratigraphic division and conduct the high-resolution cyclic stratigraphic division and correlation, and finally the division and correlation of the sedimentary facies within the high-resolution stratigraphic framework in the 1st member of the Liushagang Formation.