Abstract: The mathematicai representatives of seven decline curves were presented in this paper. By applying a standard chart for a generalized decline type curve, a correlation, analysis and study of features of these decline curves has been made, which shows, ①The Arps decline curve is described using formula of prouction decline as well as anaiytic solution of cumulative production rate. Therefore, it is easy to use them, clear for showing types of decline and popular for application. The generalized decline type curve presented on the basis of it is of a wide coverage. ②The Kopitov and the Matthews decline curves corresponded to the curve of n=0.5 of the Arps' are applicable to a reser­voir by water drive and gravity drainage. ③The Joshi decline curve is equal to the curve of n= 0 of the Arps' (i.e. the exponential decline). ④The Logistic and the Gomperts decline curves are inconsistent with the Arps’. for they all lie in range of n<0 of the Arps decline curve. They are applicable to reservoir with low viscosity under water drive. ⑤The Weible decfine curve is of great changes and wide coverage, even including the Arps decline curve, but it is only described using formula of production decline rather than analytic solution of cumulative production rate. Therefore, its appliction is restrained.

Key words: Oilfield output, Decline curve, Correlation feature