Abstract: In order to clarify the gas-water distribution law and main controlling factors of Shaximiao Formation deep source shallow accumulation tight sandstone gas reservoir in Zhongjiang. Based on the data of core analysis, well logging, gas test, production, nuclear magnetic resonance and formation water chemical analysis, the microscopic occurrence state, macroscopic distribution law and main controlling factors of formation water are studied. The results show that the formation water salinity of Shaximiao Formation is CaCl$_2$ type III$\sim$V, and the formation water exists in the reservoir in the form of bound water and capillary water. The distribution of gas and water is controlled by faults, local structures and internal heterogeneity of channels. Fault is not only the basis of gas charging, but also the passage of loss, which controls the macroscopic distribution characteristics of gas and water. Fractures develop in the near fault layer, and natural gas is dispersed during gas reservoir adjustment. Gas-water cobedding is dominant in channel near fault. The local distribution characteristics of gas and water are controlled by the heterogeneity and local structure in the channel. The lithologic (physical) sealing developed in the channel can prevent the migration and loss of natural gas to the high fault layer, and make the gas and water distribution in the sausage type, while the gas layer is developed in the lower part of the structure. The distribution pattern of gas and water in the channel without lithologic sealing is "upper gas and water", the high part of local structure is gas layer, and the lower part of structure is water layer or gas and water layer.

Key words: deep source and shallow accumulation, far source accumulation, tight sandstone gas reservoir, Zhongjiang Gas Field, gas and water distribution