Abstract
In the process of offshore natural gas extraction, natural gas hydrates tend to form within the wellbore. This secondary hydrate formation can potentially cause severe blockages. Current prediction methods primarily rely on temperature–pressure curves, which often overlook the critical effects of high-velocity fluid flow, particularly the impact and drag forces acting on the hydrates. To address this limitation, this study proposes a novel risk prediction model that innovatively decomposes the hydrate-induced wellbore blockage into three distinct stages: implantation, scour, and fracture. Each stage is mathematically evaluated using a dedicated analytical model: the impulse equation for implantation, the negative pressure suction equation for scour, and the hydrate fracture toughness equation for fracture. A region is deemed at risk of hydrate blockage only when all three stage conditions are simultaneously satisfied. Sensitivity analysis focusing on four key parameters—hydrate particle size, temperature, gas flow rate, and impact angle—revealed that increasing either the hydrate particle size during nucleation or the extraction temperature significantly reduces the risk of secondary hydrate blockage. Moreover, a typical case study demonstrated that the application of this three-stage model considerably narrows and refines the predicted risk area compared to traditional thermodynamic models. These results provide a solid theoretical foundation for accurately predicting secondary hydrate blockage risks and offer targeted strategies for flow assurance and mitigation in critical wellbore sections.