Abstract: Some gas wells in block L of Ordos basin began to produce water in varying degrees, and the water yield of some strata is as high as more than 10 m3/d, which brings great difficulties to subsequent exploration and development. By using resistivity method, acoustic method and correlation coefficient method, several sets of fluid property identification plates were established, which can identify the water-producing layers qualitatively. On the basis of qualitative identification of fluid properties, water production index is constructed by combining resistivity, acoustic wave, correlation coefficient and other parameters, and then the relationship between water yield index and water yield of gas wells was established. The results show that the higher the water yield index is, the higher the risk of water yield is. The method has certain practical value and is of great significance to the exploration and development of tight sandstone gas in this area.