Application of sandbody description of fluvial facies in one gas field of Xihu Sag

Due to the few drilling data of one gas field in Xihu Sag, the traditional methods of fluvial reservoir description by multi well data in onshore oil field are not suitable for the offshore oil and gas field. The previais cognition is too macroscopic about the distributary channel deposit of the shallow delta and the horizontally continuous distribution of reservoirs it could not guide the development and production of gas field. Based on the well data, the authors made full use of the offshore high-resolution 3D seismic data with characters of high-precision identification of fluvial reservoir and clear delineation of single channel boundary to carry out seismic sedimentology research and fine interpretation of the single channel. Four stages of single channel sandbody were identified in the target layer, and the sedimentary evolution pattern of a gradual migration to the east on the transverse and overlapping on the longitudinal was shown. The geological models have been improved and the contradiction between dynamic geological reserves and geological reserves of production wells has been solved by this research, which can be used to effectively direct the field development and production. The seismic sedimentology method is an effective method to describe fluvial sandstones in the offshore oil and gas field with less well data.