南海超深水井钻井隔水管悬挂模式的环境适应性分析

Analysis of suitability of drilling riser hang-off modes in the typhoon condition of South China Sea

每年7月至11月为南海海域台风高发期,频繁的台风严重影响了深水钻井作业效率和安全。对于超深水(水深大于1 500 m)钻井,在台风到达井位之前完成井口处理和隔水管回收,时间是一个严峻的挑战,因此一旦遭遇台风,撤离钻井平台须考虑悬挂隔水管的备用方案。以南海某超深水井(水深2 460 m)为例,分析了钻井隔水管硬悬挂和软悬挂模式下影响隔水管安全的主要因素,探讨了各个因素对波浪和海流的适应能力与敏感性。研究结果表明,多数条件下软悬挂隔水管模式对波浪和海流的适应能力更强,硬悬挂模式下隔水管系统的安全性主要受限于应力和挠性接头转角,软悬挂模式下隔水管系统的安全性主要受限于挠性接头转角和伸缩节冲程。上述认识可对深水钻井隔水管系统安装和应急悬挂条件下的作业安全提供参考。

Typhoons, which are frequent from July to November every year in South China Sea, seriously threaten the efficiency and safety of deep water drilling operations. In deep water areas（deeper than 1 500 m）, it is a big challenge to get the wellbore prepared and pull out all the riser joints before the arrival of a typhoon because of the limited T-time（typhoon preparation time）, so the hang-off mode should be considered as a backup response plan. In this paper, an ultra-deep water well（about 2 460 m）was analyzed as an example. Based on deep water well drilling data, different hang-off modes, i.e., soft hang-off and hard hang-off, were analyzed, as well as suitability of different factors to metocean. According to the analysis, in most cases soft hang-off mode is safer than hard hang-off mode. Safety performance of hard hang-off riser is limited by the stress of riser and angle of up flex joint; in comparison, soft hang-off mode is limited by angle of up flex joint and stroke of telescope joint. The findings provide references for drilling riser installation and hang-off operation in emergency situations.