| 测井数据小波变换在川中寒武系洗象池群层序地层划分中的应用 |
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| 引用本文： | 曹庆超,白壮壮,李浩武,张宁宁.测井数据小波变换在川中寒武系洗象池群层序地层划分中的应用[J].地质科技通报,2021,40(4):242-251. |
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| 作者姓名： | 曹庆超 白壮壮 李浩武 张宁宁 |
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| 基金项目： | 国家油气重大专项海外油气投资环境评估与勘探资产评价2016ZX05029-003 |
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| 摘 要： | 川中地区寒武系洗象池群由于缺乏生物化石，岩性、电性变化小，利用传统的岩心和测井等资料很难精确地划分层序。自然伽马能谱测井Th、U、K曲线的突变点能指示层序界面和最大海泛面，其Th/U和Th/K曲线不仅能够反映沉积时的氧化还原环境，还可以反映沉积水体的变化，将沉积旋回记录下来。再通过小波变换技术进行多尺度分解，得到不同级数的小波曲线。以GT2井为主要研究对象，对Th/U曲线进行多波基分解，对比发现Dmeyer小波为最优选。结合碳同位素正漂移事件，对小波变换后得到的小波曲线Th/U-d8分析，总结出2种层序划分地质模型，并将洗象池群划分为4个三级层序、8个体系域，每个三级层序由海侵体系域和高位体系域构成。同时选取了分辨率更高的小波曲线Th/U-d7和Th/U-d6曲线对四级和五级层序进行精细划分，共划分11个四级层序和25个五级层序，分别以三级层序和四级层序刻画了沉积期的相对海平面变化。该研究有助于对川中洗象池群进行精细的层序划分，推进其沉积演化与储层发育特征研究。
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| 关 键 词： | 洗象池群 自然伽马能谱测井 Dmeyer小波 小波变换 层序地层 |
| 收稿时间： | 2020-11-09 |
Application of wavelet transformation of logging data in sequence stratigraphic division of Cambrian Xixiangchi Group in Central Sichuan Basin |
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| Abstract: | Due to the lack of biological fossils and small changes in lithology and electrical properties of the Cambrian Xixiangchi Group in central Sichuan Basin, it is difficult to accurately divide sequences by using traditional core and logging data.The abrupt points of Th, U and K curves of natural gamma-ray spectrum logging can indicate sequence interface and maximum flooding surface, and their Th/U and Th/K curves can reflect not only the redox environment during deposition, but also the change of sedimentary water body and record the sedimentary cycle.Then multi-scale decomposition is carried out by wavelet transformation technology, and the wavelet curves of different series are obtained.Taking Well GT2 as the main research object, the Th/U curve is decomposed by multi-wave basis, and it is found that Dmeyer wavelet is the best.Combined with the carbon isotope positive drift event, based on the Th/U-d8 analysis of the wavelet curve obtained by wavelet transformation, two kinds of sequence division geological models are summarized, and the Xixiangchi Group is divided into 4 third-order sequences and 8 individual systems tracts. Each third-order sequence is composed of transgression systems tracts and high-stand systems tracts.At the same time, the higher resolution wavelet curves Th/U-d7 and Th/U-d6 curves are selected to finely divide the fourth-order and fifth-order sequences, which are divided into 11 fourth-order sequences and 25 fifth-order sequences, and the relative sea level changes during the sedimentary period are described by third-order sequences and fourth-order sequences respectively.This study is helpful to the fine sequence division of Xixiangchi Group in central Sichuan Basin and promote the study of its sedimentary evolution and reservoir development characteristics. |
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