摘要
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.