Abstract: Mainly based on the waterflooding data of the Karamay oil field, the salinity data of wellhead water output and other real production data,this paper applies mathematical statistics to formulate the interactive relations between the mixed formation--water resistivity and the water saturation during water--flooding,thus,to establish the variation patterns of the formation resistivity via water saturation. These patterns ,along with the resistivity data,can be used to interprete and determine the waterflooded layers more effectively.

Key words: formation resistivity, mixed formation--water resistivity, waterflooded layer