海上井口平台超压保护动态模拟研究

Dynamic simulation for overpressure protection of offshore wellhead platform

当前很多海上井口平台泄压系统采用全负荷设计理念,造成井口平台泄压系统庞大。已有文献利用数值分析提出了可接受部分井口关断失效,以降低泄压负荷的方法,并取得了工程应用。以某工程项目为例,简要介绍了工程概况,较详细论述了HYSYS动态模型的建立,并对动态模拟结果进行了分析。研究结果表明,当海底管道入口关断阀关闭,4口井中的1口井关断失效时,系统瞬时超压达到9 340 kPa,超过系统原设计压力的1.1倍,且泄放阀瞬时泄放量也超过1口生产井的产量,瞬时最大泄放量达到1.11×10~6 m^3/d,但由于核算管道和管件可承受的最高压力为10 200 kPa,所以该方案可保证生产系统安全。还对泄放阀尺寸的敏感性、关断逻辑的敏感性、阀门特性的敏感性进行了分析。

The pressure relief system of offshore wellhead platform usually adopts the full load relief design concept, which results in a huge re）ief system on p）atform. Existing literature using numerical analysis on the wellhead system proposes a method that can accept partial failure of wellhead system to reduce the relief load, and engineering application is obtained. Based on one recent project, HYSYS is used to set up dynamic model and conduct simulation, the results are analyzed. When the shut-down valve at subsea pipeline inlet is closed and one of four wells is failed to close, the instantaneous overpressure of the system reaches 9 340 kPa which is 1.1 times of the designed pressure of the system. The instantaneous relief rate of the relief valve exceeds 1.11 × 10^6 m^3/d. But the checked maximum pressure bearable for pipeline and pipe fitting is 10 200 kPa, so the production safety is ensured. The sensitivities of the relief valve dimension, shut-down logic and valve characteristic are also analyzed.