【摘要】 预测薄层厚度是精细地震勘探的重要研究目标之一。基于反射率法的正演算法考虑了一次反射波、转换波和多次波等地震波的综合响应,其结果较接近实际地震波的特征。本文采用反射率法对不同顶、底板岩性的薄煤层进行AVO模拟,并对薄煤层AVO振幅、截距/梯度以及频谱等特征进行综合分析,得出了关于单个薄煤层的AVO响应特征和规律:薄层厚度在一定范围内,其AVO振幅与厚度具有正相关关系;在截距/梯度交会图上,薄层AVO截距/梯度呈椭圆状分布,可以明显区分不同的薄层厚度;随着炮检距增加,不同厚度薄层的反射频谱差异也越明显;随着薄层厚度的增加,不同炮检距的反射频谱差异越小。这些特征和规律有助于对薄层厚度的预测。更多还原

【Abstract】 Thickness prediction of thin bed is one of the most important research objectives of fine reservoirs characterizations in seismic exploration.Modeling algorithm based on reflectivity can simulate the whole responses to thin bed including primary waves,converted waves and multiple waves,so the modeling results are closer to real seismic waves.In this paper,reflectivity method is used to model AVO for thin coalbeds with different top/bottom lithology.After comprehensive analysis of AVO amplitude,intercept/gradient and spectrum,we summarize some rules about AVO attributes with offset and thickness of thin bed:(1) Within a certain range of thin bed thickness,AVO amplitudes have a positive correlation with thin bed thickness;(2) The distribution of AVO intercept/gradient shows an elliptic shape in crossplot,from which we can distinguish thin beds with different thickness;(3) The farther the offset is,the bigger the spectrum differences become for different thickness.However,spectrum differences become smaller with the increase of thin bed thickness.These characteristics and rules are helpful to predict thin bed thickness in practice.更多还原