A new production analysis method for shale gas well based on the evaluation of decline parameters in advance

Production forecasting for multi-fractured horizontal well (MFHW) in shale gas reservoir is of vital importance to the evaluation of development potential. In this paper, we develop a new method to predict production of the MFHW under constant bottom-hole Pressure (BHP) condition. Based on the analytical model, well?s life cycle is divided into two stages, in which the decline models are established, respectively. According to these models, the decline exponent is a function of fluid properties, the pressure drawdown strategy and heterogeneous completion. It can be directly calculated without production data matching. Influence of desorption on decline exponent, calculation of ?initial pressure? during boundary dominated flow (BDF) period, are discussed. A workflow is established to perform production forecasting for a MFHW with complex fracture configuration and constant BHP in shale reservoir. A preliminary scheme is also developed to extend the workflow to variable BHP condition. Results indicate that a special hyperbolic model in which decline exponent changes as pressure drops, can be employed to forecast production during BDF. A constant decline exponent may result in an underestimation/overestimation well production, especially, in the BDF period. This new method can be used to explore how each factor impacts well productivity rigorously. Compared with conventional methods, it is of higher accuracy when making production forecast, especially for wells with short history.