Abstract: In terms of definition of growth curve used for predicting oilfield development indexes, a new growth curve of (t^b+c^t) factor type is proposed, and the calculating formula of corresponding output Q; is derived in this paper. The study showed that the maximum variation range for (N_p/N_Rmax)or m is 0~0.5450, which indicates its peak output may appear in a bit later of middle stage of development,so it agrees with the output variation regularities for absolute most of oilfields. It's Q_t vs N_p curve could be concave upward or downward during the middle stage's later time. It has four un-determined coefficients, so it is more flexible in using for output variation description. The application instance of Qingzhuji oilfield shows that the calculated curves accords with actual values very well. These all showed the proposed growth curve is very strong functional one in prediction.

Key words: oilfield, output, development index, prediction, curve