Abstract: With the rapid development of seismic exploration, it is more and more important to explore reflection reflected mechanism of thin interbeds. In order to acquire the frequency characteristic of thin bed reflection and realize its changing feature in time lapse seismic, on the one hand, the authors discussed the AVA/AVF characteristic of fluid-containing thin bed based on elastic wave theory, and carried numerical simulation experiment; on the other hand, the authors analyzed time shift characteristics of fluid-containing thin bed based on the equivalent medium theory with the actual logging data. As it is shown that the amplitude responses associated with bed-thinning is equivalent to that associated with an increase in dominant frequency. With the increase of thickness, the reflection of thin bed experiences greater fluctuations. The frequency characteristic of a thin bed extends to higher frequency with increasing of incident angle. In the water flooding extraction process of thin layer reservoir, with increasing of the water saturation, the frequency characteristic of P wave reflection extends to higher frequency, whereas that of P-SV wave reflection remains about the same.

Key words: fluid-containing thin-bed, time-lapse seismic, AVA, AVF