As we know,mobility is one of the key parameters for predicting the gas-bearing properties of low-porosity gas reservoirs.However,how to predict the mobility is always a difficult geophysical problem.In porous viscoelastic medium,the existence of fluid leads to different degrees of seismic wave dispersion and attenuation,and many researches have shown that P-wave dispersion is related to the fluidity of the fluid which is the ratio of permeability to fluid viscosity.Thus,the fluidity can be used to assist the prediction of fluid viscosity and permeability.In this paper,based on Zoeppritz approximate equations expressed in ray-domain by Wang Yanghua,the frequency factor is introduced into AVO analysis,and frequency-dependent AVO expressions is deduced in ray domain.The authors also present a frequency-dependent attributes expression to measure the velocity dispersion and analyze the velocity dispersion characteristics with frequency variation,with the features of velocity dispersion varying with frequency,by using expressions of frequency-dependent attributes.Then,the authors combine the velocity dispersion and fluidity of the fluid.Finally,the authors apply the proposed method to oil and gas detection in lithologic gas reservoir which is characterized by high-temperature,high-pressure in DF district of Yinggehai basin.The application results show that the velocity dispersion can effectively predict the fluidity of fluid and the gas-containing property of the reservoir, and the effectiveness of this method is demonstrated.