Unified early-to-late time forecasting method for multi-fractured horizontal wells in unconventional gas reservoirs with fracture interference effects

Abstract

This paper presents a unified forecasting approach for multi-fractured horizontal gas wells from early to late time considering inter-fracture communication effects based on Green’s Function Method. The proposed methodology circumvents the need to determine the end of linear flow time currently required in available forecasting methods. As a result, the application of independent solutions for specific flow regimes is avoided, diminishing the degree of uncertainty for the analyst. The present work also aims to decrease the degree of empiricism in current forecasting models based on pseudo-time and DOI by addressing the nonlinearity in the flow equation in a rigorous manner. The proposed methodology is validated against finely gridded numerical simulation models to demonstrate the capabilities of the proposed approach to forecast multi-fractured horizontal gas well performance. Further comparative studies against available approximate methods, such as classical and pseudo-time-based analytical solutions, are also considered to showcase the limitations in the current state-of-the-art of production data analysis of unconventional gas wells. It is evidenced that for the cases of higher pressure drawdown, where the nonlinear behavior of gas flow is exacerbated, current approaches fail to predict the expected system behavior. This finding confirms the importance of the proposed methodology, which consistently yielded the best matches given its capabilities to incorporate nonlinearity in a more rigorous manner.