Abstract: The characteristics of well logging curve changing of watered out formation of Fuyang reseivoirs in Xinli oilfield is discussed, and the responses of well logging are analyzed. Based on the parameters such as water production rate and well test data, the grade of watered out formation are determined. database of well logging response of watered out formation is established, from which, a subordinate function and maximum fuzzy degree of membership to identify watered out formation, and classify different grades. The application shows the method is in accordence with the real situation well, a good agreement with the production data in watered out formation evaluation.

Key words: Xinli oilfield, watered out formation, well logging interpretation, watered out grade, fuzzy identification