General optimization framework of fractured horizontal wells in high-sulfur gas reservoirs using response surface methodology

In high-sulfur gas reservoir development, vertical fractures induced by hydraulic fracturing effectively expand the drainage area and improve gas well productivity. However, with production progression, sulfur deposition blocks seepage channels, impairing gas well productivity. Therefore, this study presents the first sulfur deposition model for fractured horizontal wells, incorporating dynamic coupling of reservoir temperature–pressure effects with non-Darcy fracture flow via an updated correction factor, validated through numerical simulations. In addition, sensitivity analyses were conducted for fracture half-length, fracture conductivity, production rate, and fracture number. Finally, comprehensive parameter studies were performed using Response Surface Methodology (RSM). Results indicate that sulfur saturation in fractures gradually decreases along the fracture length, with higher saturation at the fracture heel and top formation and lower values in the middle section. Fracture half-length exhibits a minimal impact on sulfur deposition within fractures and adjacent formation. Higher fracture conductivity increases sulfur deposition in fractures and reduces deposition near the fracture heel but increases deposition in the top formation. Higher production rate elevates sulfur saturation in both fractures and formation. Increasing fracture number reduces sulfur saturation in fractures and near-fracture formation while diminishing saturation heterogeneity across the formation. The RSM-optimized parameters result in a reduction in sulfur saturation within fractures by more than 90% compared to the initial case. This study provides an effective predictive model for sulfur deposition in fractured horizontal wells and a general framework for optimizing the parameters of horizontal wells in high-sulfur gas reservoirs, providing practical guidance for optimizing fracturing parameters and production schemes in high-sulfur gas reservoirs.