Research progress and development prospects on critical challenges in deepwater riserless drill string dynamics

With the ongoing expansion of oil and gas drilling into deeper waters, riserless drilling technology has shown prominent advantages in deepwater drilling applications. The structural design and operational mechanism of riserless drilling make drill strings more vulnerable to stochastic ocean loads, requiring thorough investigation of critical factors influencing drill string dynamics in deepwater riserless operations to maintain drilling stability. Accordingly, this work initially synthesizes computational approaches for drill string external loads, elucidating how multiphysics-coupled loading mechanisms impact both drilling safety and operational efficiency. Furthermore, this work investigates fundamental challenges in drill string dynamics, including riser vortex-induced vibrations (VIV) in water columns and nonlinear drill string vibrations in formation sections, establishing connections between oceanic loads and traditional drilling dynamics. Moreover, this work systematically evaluates both active and passive vibration mitigation techniques, including VIV suppression for marine riser segments and formation vibration control methodologies. This work concludes by examining next-generation drilling control systems that feature intelligent data transmission, data-driven modeling, and smart control technologies. These elements collectively form a “perception-modeling-control” closed-loop system to overcome the time-delay limitations of traditional methods. The findings establish a theoretical foundation for deepwater drilling parameter optimization, safety risk mitigation, and efficiency improvement.