利用小波变换从测井曲线中提取米兰柯维奇周期  

Extracting the Milankovitch Cycles from Logging Data by Wavelet Transformation

作　　者：喻小涛 胡光明[1] 罗水亮[1] 奉伟 李宇 张志鹏 李志威 

机构地区：[1]长江大学地球科学学院,湖北武汉430100 [2]中国地质大学(北京)能源学院,北京100083

出　　处：《长江大学学报（自然科学版）》2018年第7期45-48,91,共5页Journal of Yangtze University(Natural Science Edition)

基　　金：国家自然科学基金项目(41472097);油气资源与探测国家重点实验室开放课题(PRP/open-1608)

摘　　要：自米兰柯维奇理论提出以来,如何从一段测井曲线中提取相应的3个米兰柯维奇周期(斜率、岁差、偏心率)仍是一个经常探讨的问题。以鄂尔多斯盆地二叠系山西组1段~石盒子组8段湖盆中心汇水区的A299井、A1116井、A1118井、A1022井为例,结合Matlab软件对该问题进行了探索。首先采用db5小波对研究层段各井的自然伽马测井数据进行连续小波变换,得到不同尺度下的频率,进而计算相应的频率比值;同时根据前人的成果计算出与研究层段所处时代的理论天文周期、理论频率比值;然后将研究层段频率比值与理论频率比值进行对比,筛选出与米兰柯维奇周期对应的小波频率,最终确定与各米兰柯维奇周期相关的小波曲线分别为d9、d6、d5(其中d9对应的是偏心率,d6对应的是斜率,d5对应的是岁差)。该研究成果对于更精确地划分地层及校准天文地质年代具有重要意义。How to extract the corresponding Milankovitch Cycles(obliquity,precession and eccentricity)from log curves was a frequently discussed problem since the Milankovitch Theory was proposed.By taking Wells A299,A1116,A1022 and A1118 located in Segment Shan 1-Segment He 8 of Permian in Ordos Basin for example,the issue was studied in combination with MatLab software.Firstly,the natural gamma logging data of each well were processed by db5 wavelet forcontinuous wavelet transform to obtain the frequencies of different scales,and then corresponding frequency ratios were calculated.Secondly,on the basis of previous research results,the theoretical astronomical period and theoretical frequency ratios were calculated.Thirdly the frequency ratio from logging data was compared with the theoretical frequency ratio,and then the Milankovitch Cycle was selected.Finally,the wavelet curves related to each Milankovic Cycle are confirmed as d9,d6,d5.The d9 corresponds to eccentricity,the d6 corresponds to obliquity,and the d5 corresponds to precession.The research results are of great significance for more accurate division of strata and calibration of astronomical age.

关 键 词：米兰柯维奇旋回 天文周期 连续小波变换 频率比值 MATLAB软件 

分 类 号：P631.84[天文地球—地质矿产勘探]