Abstract: In the course of petroleum exploitation，it is often necessary to do the study of gas-drived enhanced exploitation to improve the development efficiency in thin sand-mudstone reservoir.The seismic data acquired from the heterogeneous thin sand-mudstone reservoirs containing oil or gas are migrated and stacked and are processed by using cross-equalization method.The different characteristics，such as frequency，amplitude，etc.，of different liquids are concluded，more over，the features of time-lapse seismic difference are analyzed.The result of the study can present the gas-injection advancing-frontier sweep zone and the distribution of residual oil，and can be used to define the amplitude of elastic difference between different liquids（e.g.gas，and oil，etc.）The results show that the seismic responses of the heterogeneous thin reservoir is obviously different when the different fluids，such as gas or oil，are stored in the thin reservoir，and the time-lapse seismic difference-attributes are different.The result can provide the evidence to recognize the fluid features of thin reservoir and to guide the exploration and development of petroleum.

Key words: heterogeneity, thin reservoir, gas injection advancing frontier, time-lapse monitoring, cross equalization, seismic