Tight glutenite reservoirs are known for strong heterogeneity, complex wettability, and challenging development. Gas-Assisted Gravity Drainage (GAGD) technology has the potential to significantly improve recovery efficiency in glutenite reservoir. However, there is currently limited research on GAGD processes specifically designed for glutenite reservoirs, and there is a lack of relevant dimensionless numbers for predicting recovery efficiency. In this study, we developed a theoretical model based on the characteristics of glutenite reservoirs and used phase-field method to track the oil–gas interface for numerical simulations of dynamic GAGD processes. To explore the factors influencing gas-driven recovery, we simulated the effects of strong heterogeneity and dynamic wettability on the construction process under gravity assistance. Additionally, we introduced multiple dimensionless numbers (including capillary number, viscosity ratio, and Bond number) and conducted a series of numerical simulations. The results demonstrate that gravity enhances the stability of the oil–gas interface but causes unstable pressure fluctuations when passing through different-sized throat regions, particularly leading to front advancement in smaller throats. Although strong heterogeneity has negative impacts on GAGD, they can be mitigated by reducing injection velocity. Increasing oil-wettability promotes oil displacement by overcoming capillary forces, particularly in narrower pores, allowing residual oils to be expelled. Among the dimensionless numbers, the recovery efficiency is directly proportional to the Bond number and inversely proportional to the capillary number and viscosity ratio. Through sensitivity analysis of the dimensionless numbers’ impact on the recovery efficiency, a new dimensionless N_Glu considering heterogeneity is proposed to accurately predict GAGD recovery of tight glutenite reservoirs.