Abstract:The gas reservoir of mid Tenggeer formation in Lower Cretaceous system on Aershan anticline in Erlian basin is 500m deep. It is a shallow layered gas reservoir on a faulted anticline;in addition,the surface condition above it is favourable. As a result it has the typical seismic reflection characteristics of gas reservoir:1)dim spot at top interface of gas reservoir,2)bright spot at bottom interface of gas reservoir,3) flat spot at gas-water contact,and 4) seismic response shape of gas reservoir. The gas-reservoir section shape,gas column height,gas layer groups,thickness of each gas layer group,and top or bottom interface which were discoveyed by drilling in Aershan region are coincident with those shown by seismic sections. Flat spot reflection consists of four segments,which embody respectively the gas-water contacts of four gas-layer groups. That the four gas-layer groups have the same deep gas-water contact means that they have the same boundary water and pressure system. Their bottom interfaces all produce bright spots,and their top interfaces all bring dim spots.