An Optimization Method of Top Tension in Drilling Riser–Conductor System

Drilling riser–conductor system is crucial to the offshore drilling. Complex marine environment can give rise to a series of problems such as buckling and stability on riser–conductor system. A novel method that introduces the optimization of top tension and calculates axial force has been proposed. Effective axial stress equations for the whole riser–conductor system are established in this paper considering these factors such as rising velocity of drilling fluid, temperature, pressure, and current force. Then, the neutral point of effective axial stress is introduced in marine drilling and top tension can be adjusted to ensure the neutral point is located at BOP. Compared with other methods, a case study shows that a higher accuracy of effective axial stress can be expected with this method. Meanwhile, top tension should be optimized to allow the neutral point to locate at BOP and ensure the BOP keep enough bending strength.