Abstract: The empirical production decline analysis methods inside and outside China were investigated extensively for further understanding these methods and promoting their application in development of shale gas reservoirs. The Arps, power exponential, stretched exponential and Duong decline analysis methods were elaborated in terms of source, decline model, typical curve, application condition, limitation and improved method, and finally the key issues related to empirical production decline analysis methods in future study were proposed. The study results indicate that all the empirical production decline analysis methods are capable of forecasting both production and EUR, but they can only analyze the production data under constant or approximately constant bottom-hole flowing pressure, and require continuous and stable production data without long-term shut-in. The difference in these empirical production decline analysis methods lies in different flow regime. Arps decline model and modified hyperbolic decline model are only available to boundary-dominated flow regime. Stretched exponential decline model and Duong decline model are useful for linear flow regime. Modified Duong decline model, modified power exponential decline model and power exponential decline model are applicable for both linear and boundary-dominated flow regimes. It is critical to identify and classify the flow regime in a shale gas well for application of empirical production decline analysis. In shale gas wells in China, it is hard to keep constant or approximately constant bottom-hole flowing pressure during production, then how to correct such production data to the data under constant or approximately constant bottom-hole flowing pressure is the emphasis in future study on empirical production decline analysis methods.

Key words: shale gas, empirical production decline analysis, Arps decline, power exponential decline, stretched exponential decline, Duong decline, flow regime