Enhanced modeling of deep-water condensate transport and dispersion in the South China Sea

Abstract

With the increasing global development of deepwater condensate reservoirs, the potential risks of leaks from condensate gas and oil are significant. However, existing oil spill models have limitations in simulating these leaks, particularly in handling multiphase bubbles and hydrate morphology. This study adopts thermodynamic models to simulate the phase change of condensate gas during deepwater ascent, accounting for multiphase bubble partitioning. The effect of hydrate shell morphology evolution on leakage transport is improved to enhance model applicability and accuracy. Comparative analysis with laboratory and field data reveals an average relative error of less than 10 %, demonstrating robust predictive capability. The model was applied to a short-term leakage scenario in a South China Sea condensate field. Results showed a complete depletion of gas-phase components in the condensate bubbles, with 18 % of liquid-phase components (C₅ and C₆) remaining to be transported to the far field. Additionally, a 0.55 km² oil slick was detected 360 m southwest of the leakage point after 72 h of reciprocating flow. This research provides a solid theoretical foundation for emergency response and consequence assessment of subsea oil and gas pipeline leaks, advancing related research and applications.