The typical characteristics of the waterflooded layer are the reduction of oil-gas saturation and the change of conductivity of the mixed formation water. The higher the degree of flooding, the lower the resistivity of the formation water flooded and sewage flooded reservoirs; the resistivity will first decrease and then increase, presenting a "U" or even "S" shape change of freshwater flooded reservoirs. And the changes in the conductivity of mixed formation water will inevitably lead to changes in spontaneous potential, resulting in the abnormal amplitude changes, the abnormal positive and negative inversion, and the baseline shift. On the basis of the typical characteristics of the known flooded layer on the conventional logging curves, a comprehensive analysis of the logging curves can be used to identify the unknown flooded layer, or the logging data can be used to construct a transaction map todetermine the flooded layer.