ABSTRACT

Offshore drilling activates have been significantly impacted by severe weather conditions as oil and gas development has moved into deeper water. Under the situation of imminent arrival of a typhoon, emergency retrieval of the whole drilling riser string is time consuming and tedious. A specialized soft hang-off system to improve the adaptability of the drilling riser system under hang-off operations is developed to solve the low-efficiency and time limitation for retrieval all drilling riser joints during in extreme storm environment. By using the hang-off joint and hydraulic compensation systems, the device can perform the dynamic compensation of the riser during typhoon and improve the moonpool interference performance, so as to greatly improve the safety of drilling riser during typhoon period, and can be applied in transit during cross-wells operation with a relatively higher transit speed. Global fatigue analyse to predict the wave induced fatigue and VIV fatigue damage for deepwater drilling riser and hang-off joint system during hang-off operations in extreme environments are conducted to confirm the proposed design of the hang-off joint system. The specialized system and global fatigue analytical methodology provides safety guarantee during deepwater drilling operations.

INTRODUCTION

The frequently typhoon in South China Sea that battered the offshore facilities (Xu et al., 2015; Wang et al 2021a) have prompted many operators and drilling contractors to rethink the way their drilling risers are designed for emergency disconnection and retrieval before the typhoon or hurricane arrives. When drilling in very deep water depths, retrieval of the drilling riser is time consuming and tedious; and in emergency situations like the imminent arrival of a typhoon, the drilling rigs risk not being able to recover the drilling risers in time before the evacuation of personnel or sailing for shelters, with potentially devastating consequences.

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