Abstract: In the initial stage of production of oil wells, affected by the production system, the production is unstable, and the conventional production decline analysis method is not applicable. To solve this problem, by means of transforming the variable production pressure solution of oil wells into the constant production pressure solution under Duhamel’s principle, a data analysis method suitable for early variable output production of oil wells is obtained through introducing material balance time and normalized production, and the mathematical model is used to fit the processed data, so as to obtain the inversion of reservoir parameters. Taking Well P1-2 in Daqing Oilfield as an example, the daily oil production and bottom-hole flow pressure production data were used to quantitatively analyze the production dynamics of a single well, and the regularized production-material balance time double logarithmic curve chart was plotted to perform the quantitative inversion interpretation of the real physical parameters of the formation. The results show that after the method is used to analyze the production data of variable output, the curve exhibits the characteristics of unstable flow and distinct segmentation of the boundary flow in the conventional decline plot. The practical application shows that the average error of this method is less than 10%, and the accuracy is high. This study can provide theoretical guidance for the early productivity analysis of oil wells.

Key words: production decline analysis, Duhamel′s principle, normalized production, parameter inversion