薄层峰值频率特征分析

Analysis of peak frequency characteristics of thin bed

当前大多数油田都已进入勘探开发后期,薄层及薄互层已成为地震勘探的主要目标.根据沉积的特征可将薄层划为四种类型,对不同薄层类型进行地震反射特征分析研究具有重要的理论意义和实际参考价值.本文首先对地震波垂直入射情况进行分析,得出薄层厚度与峰值频率的定量关系式,并对其进行高阶近似,得到适用于不同类型薄层的峰值频率随厚度变化的公式.然后对各型薄层采取不同参数,得出峰值频率随着薄层顶底反射系数之比变化的规律.最后,本文又对薄层进行AVO分析,研究各类薄层峰值频率随入射角变化的特征,并探讨了厚度和子波峰值频率对薄层峰值频率的升频作用,对薄层峰值频率特征得出了初步结论,并为实际地震资料处理提供参考.

With most of the oil fields entering into the final stage of exploration and development, thin reservoir has become the main target of seismic exploration. According to the sedimentary characteristics, thin bed can be divided into four types. Investigation on seismic reflection characteristics of different thin bed type plays an important theoretical significance and practical reference value. The quantitative relationship between layer thickness and the peak frequency is achieved by the analysis of seismic wave vertical incidence. By high order approximate formulas, we get equation of peak frequency with thickness for different kinds of thin bed. Then take the different parameters for each type, we conclude that the peak frequency changes along with reflectance ratio of the top and bottom of thin bed. Finally, the paper use AVO analysis to thin bed, and reserch on the peak frequency characteristics of each type changes with the angle of incidence, and discuss the effect of thickness and peak frequency of wavelet on raising peak frequency of the thin bed. The paper draws the preliminary conclusion of peak frequency characteristics of thin bed and provides reference for practical seismic data processing.