Techno-Economic Assessment of Fracturing-Assisted Thermal Stimulation for Gas Hydrate Extraction: Field-Scale Numerical Simulation and Net Present Value Analysis

Horizontal well fracturing and thermal injection co-stimulation is widely regarded as a key technology for enhancing the development potential of gas hydrates in the Shenhu Area of the South China Sea, yet its economic feasibility has not been systematically evaluated. In this study, an improved net present value (NPV) economic evaluation model integrating the entire development process of drilling, fracturing, and injection-production was developed, and a techno-economic assessment was conducted based on field-scale numerical simulation data. The results show that neither fracturing nor thermal stimulation alone can achieve positive economic returns; although their combination significantly improves gas production performance, its economic viability is highly dependent on heat source cost and horizontal section length. When the heat source cost decreases from 0.8 to 0.2 RMB/kWh, and the horizontal section length increases from 300 to 1500 m, the NPV increases from –28.99 to 41.88 million RMB. Sensitivity analysis reveals that gas price is the most sensitive factor affecting NPV (variation range of 59.71 to 103.5 million RMB), followed by gas–liquid separation efficiency. It is recommended that prioritizing low-cost heat sources (e.g., geothermal or industrial waste heat), combined with long horizontal section design and downhole water control technologies, is the key strategy to ensure project profitability. Even for the direct warm seawater injection scheme, the horizontal section length should not be less than 1000 m.