Abstract: The late Mr.Weng proposed logistic cycle model in 1984, which can be used to predict watercut and water-oil ratio and widely applied in oilfields. Based on the deduction of Weng' s logistic model in theory, this paper verified the unreasonableness of empirical formula(WOR =be^-at/c)presented by John Fisher.Meanwhile, on the basis of field application of it, it is pointed out that Weng's logistic model is applicable to predict watercut and water-oil ratio of oilfields which current water cut is less than 70 %.

Key words: Water drive, Oilfield, Water cut, Prediction, Model