Abstract: Resistivity difference between oil layer and water layer is unconspicuous in target area. It is hard to identify the types of fluids in formation utilizing the conventional resistivity log. Under mud invasion, resistivities of oil layer and water layer in different radial depth are influenced by various factors. Based on Archie formula, we can know the changes of fluid content in formation through calculating radial resistivities of water layer and water saturation coefficient of different radial depth in other layers utilizing array induction imager log data, so we can identify the types of fluids in formation.