中文摘要：

在碳酸盐岩台地沉积层序的研究中，通过旋回计数和厚度测量，采用费希尔图解法解析高频米级旋回或副层序的叠置形式和空间结构，进而标定三级沉积层序的界面，是目前普遍采用的一个方法。但是，这一方法目前主要用于露头层序地层学研究，而在地下油气勘探区受到极大的限制。文中提出了一种新的计算方法，它可以根据测井资料求取任一地层段沉积旋回的个数和厚度。根据数值模拟，详细讨论了海平面变化周期和幅度与沉降速率、沉积速率的相关关系，提出高频沉积旋回的分布模式和叠加样式可以指示低频海平面变化的轨迹，这为划分三级沉积层序、标定层序界面提供了理论依据。最后，以川I西北地区中三叠统雷口坡组为例，说明了应用自然伽马测井资料进行数据处理的流程和步骤，以及根据旋回厚度累积偏差曲线标定层序界面的位置、识别旋回谱系标志。

英文摘要：

The Fischer Plot is a graphic method about analyzing numbers and thicknesses of meter scale cycle units or parasequences of carbonate platform successions. The method is used to analyze the stacking patterns and hierarchical architectures of high frequency cycles and then to define depositional se- quence surfaces. This method has widespread application in field stratigraphic sections, but it meets ob- stacles and limitations in subsurface petroleum exploration districts. A new calculation method is proposed in this paper and the cycle numbers and thicknesses can be detected by means of well log data processingin any stratigraphic intervals. The interplays among amplitudes and periodicities of eustatic sea levels, subsidence rates, and sedimentation rates were discussed in detail according to numerical simulation re- suits. It is suggested that ordered stacking patterns of high frequency cycles indicate low frequency sea level fluctuation pathways. This provides us theoretical basis to distinguish the third order depositional se- quences and surface location with well depth. The Middle Triassic Leikoupo Formation in the northwestern Sichuan Basin is taken as a case study, processing methods and procedures were demonstrated using natu- ral gamma ray logging data. Discriminant markers for depositional sequence surfaces and multiple cyclic hierarchies were presented by graphing cumulative departure curves from mean cycle thickness as a func- tion of cycle number or well depth.