This paper investigates the simulation and control strategies for the longitudinal propagation of acid fractures in a low-permeability reservoir containing bottom water, specifically in the Anyue gas field of the Sichuan basin. The reservoir is characterized by strong heterogeneity, low porosity, and permeability, with high water saturation and a homogeneous bottom-water interface. Deep acid fracturing is an effective method for enhancing well production, but it poses significant challenges due to high-angle natural fractures, small vertical stress differences, and proximity to the gas-water interface. The study develops a 3D numerical model to analyze the initiation and expansion of acid fractures, considering geological and engineering factors such as stress differences, fracture displacements, and fluid viscosities. Key findings include: 1. **Pressure Difference as the Main Controlling Factor**: The pressure difference is the primary factor controlling the height of acid fractures, followed by reservoir thickness, interlayer thickness, and fluid viscosity. 2. **Technical Countermeasures**: Proposals for controlled fracture and high-acid fracturing tailored to different reservoir characteristics are provided, with optimized design parameters. 3. **Control of Vertical Extension**: Effective control of the vertical extension of acid fractures maximizes single-well production while avoiding interference from the lower water layer. 4. **Model Verification**: The model's accuracy is verified through comparisons with experimental results and other models, demonstrating its reliability in predicting fracture behavior. The study provides theoretical guidance for the application of deep-acid-fracturing techniques in low-permeability bottom-water gas reservoirs, enhancing understanding and control of fracture propagation.This paper investigates the simulation and control strategies for the longitudinal propagation of acid fractures in a low-permeability reservoir containing bottom water, specifically in the Anyue gas field of the Sichuan basin. The reservoir is characterized by strong heterogeneity, low porosity, and permeability, with high water saturation and a homogeneous bottom-water interface. Deep acid fracturing is an effective method for enhancing well production, but it poses significant challenges due to high-angle natural fractures, small vertical stress differences, and proximity to the gas-water interface. The study develops a 3D numerical model to analyze the initiation and expansion of acid fractures, considering geological and engineering factors such as stress differences, fracture displacements, and fluid viscosities. Key findings include: 1. **Pressure Difference as the Main Controlling Factor**: The pressure difference is the primary factor controlling the height of acid fractures, followed by reservoir thickness, interlayer thickness, and fluid viscosity. 2. **Technical Countermeasures**: Proposals for controlled fracture and high-acid fracturing tailored to different reservoir characteristics are provided, with optimized design parameters. 3. **Control of Vertical Extension**: Effective control of the vertical extension of acid fractures maximizes single-well production while avoiding interference from the lower water layer. 4. **Model Verification**: The model's accuracy is verified through comparisons with experimental results and other models, demonstrating its reliability in predicting fracture behavior. The study provides theoretical guidance for the application of deep-acid-fracturing techniques in low-permeability bottom-water gas reservoirs, enhancing understanding and control of fracture propagation.