以米兰科维奇周期为约束的层序地层划分研究
Study on Sequence Stratigraphic Division by Using Milankovitch Cycles as Constraints
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摘要: 基于层序地层学和旋回地层学理论,以贵州盘县3井为例,采用db5小波对其自然伽马(GR)测井数据进行小波变换,并对各小波系数曲线进行快速傅里叶变换,选用米兰科维奇周期最佳匹配分析方法,根据其比值与米兰科维奇天文周期比例关系的对应性,对识别出来的优势周期进行剔除和选择,确定了与各米兰科维奇周期相关的小波曲线分别为d3、d5、d6和d8。基于米兰科维奇周期对高频层序的控制作用,将米兰科维奇旋回的识别和层序地层的划分对比相结合,以识别出来的米兰科维奇旋回作为约束条件,进行测井层序的划分研究。结果表明,在钻井中米兰科维奇旋回曲线特征清晰,划分出4个三级层序和2种体系域,所划分的层序地层与实际地质情况是基本吻合的。Abstract: On the basis of the sequence stratigraphic theory and cyclic stratigraphic theory,the data of GR well logging curve from Well Panxian 3 were processed t hrough db5 wavelet analysis and fast fourier transformation. According to Milankovitch cycles best matching method and the corresponding relations between the ratio of Milankovitch cycles, the wavelet scales of Milankovitch cycles which have been determined by rejecting and selecting the dominant periods in the strata were d3,d5,d 6 and d8. Based on the control action for the high frequency sequence and combined the recognition of Milankovitch cycles with the division and correlation of sequenc e stratigraphy,the stratigraphy division and correlation of the wells were carried out by using Milankovitch cycles as rulers. The results show that the features of Milanko vitch curves were made clear,four third-order sequences and two system tracts were classified,the divided sequence stratigraphy basically tallied with the actual geologi cal situation.