The intricate multi-scale seepage mechanisms within shale gas wells pose significant challenges in developing precise mathematical models for predicting gas production rates. This study leverages the material balance method to streamline the complex modeling of seepage behaviors, thereby facilitating both theoretical analyses and practical applications in shale gas exploitation. By examining the unique seepage dynamics across the fracture network of horizontal wells, a segmented material balance equation is introduced. This novel equation integrates the distinct flow characteristics of the matrix, natural fractures, and hydraulic fractures, and is further enhanced by incorporating the laws of pressure propagation specific to each segment. A dynamic method for zonation determination, based on the progression of these pressure fronts, is proposed to adapt to the changing seepage mechanisms over time. Adopting the material balance framework, this study delineates a methodology to quantify the varying contributions of different seepage mechanisms to gas production. It establishes a set of calculation parameters and a fitting technique tailored to assess the contributions of gas content, water production, and gas production rates under the influence of multiple factors including fracturing attributes, reservoir properties, and phase behavior processes such as adsorption–desorption and imbibition. The model is validated through a case study, showcasing its effectiveness in predicting changes in productivity and, importantly, in identifying the shifting roles of various seepage mechanisms throughout different stages of production. The findings illuminate the dynamic interplay between seepage mechanisms in shale gas wells, offering critical insights for optimizing production strategies and advancing our understanding of shale gas reservoir behaviors.