Summary In recent years, the oilfield in Bohai Bay has made significant progress in the exploration of reservoirs with alternative fluvial and lake deposition, and multiple large and medium-sized oil fields have been discovered. Different from typical reservoir of fluvial facies, composite sand bodies with complex narrow channel are widely developed during the alternative fluvial and lake deposition period. During this period, the river channels were densely developed, with narrow width and thin thickness, which required high accuracy in identifying reservoirs from seismic data. In addition, composite sand bodies composed of a large number of narrow river channels interwoven with each other have complex internal connectivity relationships, and the risk of multi fluid system development is high, which affects the reasonable deployment of development well networks. Thus, Firstly, this paper introduces geological statistical prior information in the process of spectral inversion, which effectively expands the seismic data spectrum, improves the vertical identification accuracy of seismic data, and enhances the planar continuity of narrow channels. Secondly, fine description of composite sand bodies is carried out through multi-attribute CMY fusion technology. Based on the above research, it effectively guarantees the successful implementation of the development plan for the B oilfield of Bohai bay.