Safety Assessment On Vortex-induced Vibration Of Marine Drilling Riser System

In China, the exploration and exploitation of ocean oil and gas resources is moving into deep water. Drilling riser is an essential device for Marine drilling operation, so its safety and reliability must be guaranteed. Vortex-induced Vibration (VIV) is one of the most important issues influencing the drilling work safety and it must be taken into account during riser designing and running process.This paper mainly presents research on Vortex-induced Vibration of deepwater drilling risers. Prediction techniques and fatigue analysis methods for VIV of drilling risers are investigated; a simplified method for fatigue life assessment and a finite element method for fatigue analysis are proposed. Emphases are placed on VIV of traditional drilling risers and ABS drilling riser systems. The influence of basic parameters on VIV of traditional drilling risers is investigated, which can be a reference for the design of drilling risers; the efficiency of VIV suppression devices and staggered buoyancy modules are quantitatively analyzed; a combinative plan for VIV suppression is proposed, which combines VIV suppression devices and staggered buoyancy modules, and its efficiency is proved to be fairly well. The research on VIV of ABS drilling riser systems is simultaneous with foreign researches, the weakest position of ABS system is pointed out, which connects ABS and tie-back casing; the design of bending stiffener is amply analyzed; a plan of adding flex-joint to the bottom of ABS is proposed, according to the research results, the flex-joint can eliminate the stress concentration caused by ABS essentially and reduce fatigue damage of the total system remarkably.