油气泄漏火灾下FPSO热-结构耦合分析

针对FPSO油气泄漏引发的火灾风险,建立热-结构耦合分析模型,采用ANSYS Workbench软件对工艺区设备泄漏、火灾事故及灾害下结构响应进行数值模拟,重点分析工艺处理模块Ⅰ区设备温度分布及热变形情况。通过对比不同油气泄漏速率和环境风速下火灾发展、危害范围和结构受损程度,探讨油气泄漏孔孔径和风速对火灾后果的影响。结果表明:稳定发展火灾下工艺处理模块Ⅰ区设备周围环境维持高温状态;泄漏孔附近结构受损最严重,原油热处理器受火灾损害发生大的变形;随泄漏孔孔径增大,火灾危害范围扩大,结构发生大变形的区域增大,d=40 mm时原油热处理器受损最严重,d=60mm时结构受损区域最大,大部分结构受损程度加剧;来风风速的变大使得火灾更加剧烈,设备受损区域扩大,受损程度加剧,结构火灾风险加大。     

Uncertainties in a risk management context in early phases of offshore petroleum field development

The current risk management approach for the Norwegian offshore petroleum industry came into effect in 2001 and has been stable with minor changes for 15 years. Relatively few new installations were slated for development until quite recently, and several new projects have been started in the last few years. The paper considers the risk management approach in the pre-FEED phase and builds on two case studies selected from the most recent cases. These case studies have been evaluated with respect to how uncertainties are considered in the early phase, based on the submission of the Plan for Development and Operation, their evaluations by authorities and the supporting documents. Both case studies involve new concepts for which there is no experience from similar environments and/or water depths. In spite of what could have been expected, the case studies conclude that uncertainties have not been in focus at all during concept development. This appears to be definitely the case for the licensees, but also to be the case for the authorities. Some suggestions are presented for what could have been considered by the licensees and authorities.     

某海域极端环境下15万吨级FPSO波浪荷载数值研究

目的 评估在役15万吨级FPSO在某海域百年一遇极端波浪作用下典型横剖面的水动力特性,进而得到FPSO的极值荷载,作为FPSO返坞改造的关键控制参数。方法 基于国产自主三维频域线性势流软件COMPASS-WALCS,建立15万吨级FPSO湿表面网格模型,根据三维绕射-辐射理论,计算湿表面上的水动力荷载,将每个绕射单元上的水动压力直接映射到结构模型上进行计算。采用谱分析方法对百年一遇海况进行分析,得到短期运动极值响应。对响应幅值算子(RAO)和波能谱密度进行谱分析,得到极端波浪下的响应谱,进而得到浮体运动和波浪荷载短期预报各种统计值,利用统计方法求得短期响应的最大值。结果 计算了船中部Fr143横剖面的载荷极值,即垂向弯矩、垂向剪力、剖面型心加速度等,发现船舶迎浪时弯矩值最大,随着浪向角增大,弯矩值逐渐减小,剖面垂向剪力则随着浪向角增大逐渐增大。结论 FPSO在极端波浪作用下,其大迎浪角条件下荷载更加危险,需要给予格外关注。     

压载舱锌阳极失效原因分析及实验室研究

目的 找到压载舱锌阳极失效原因,并提出整改方案。方法 对服役环境进行调研、阳极化学成分检测、电化学性能检测以及阳极表面形貌检测。结果 干湿交替以及高温的环境是造成锌阳极发生钝化的主要原因。在干湿交替环境下,阳极腐蚀表面晶粒松散,晶界宽度大,发生晶间腐蚀和晶粒脱落,造成了阳极失效。结论 通过该项目的实验研究,得出了锌阳极的适用条件,在干湿交替的环境以及高温环境(50 ℃)下,不推荐使用锌阳极,建议使用铝阳极。     

Allocation of performance shaping factors in the risk assessment of an offshore installation

Offshore oil production is one of the most important human productive activities. There are many risks associated with the process of constructing a subsea well, pumping oil to the platform, and transporting it to refineries via underwater pipes or oil tankers. All actions performed by workers in those operations are influenced by specific working conditions, involving the use of complex systems. Contextual factors such as high noise, low and high temperatures and hazardous chemicals are considered to be contributors to unsafe human actions in accident analysis and also give a basis for assessing human factors in safety analysis. Some failure modes are particularly dangerous and can result in severe accidents and damage to humans, the environment and material assets. Fires and explosions on oil rigs are some of the most devastating types of offshore accidents and can result in long-term consequences. The most typical root causes related to accidents include equipment failure, human error, environmental factors, work organization, training and, communication, among others. The principal objective of this study is to propose a methodological framework to identify the factors that affect the performance of operators of an offshore unit for oil processing and treatment. In this phase, an ergonomics approach based on operators' work analysis is used as a supporting tool. After identification of factors that affect the performance of operators, a decision-making model based on AHP (analytic hierarchy process) is applied to rank and weight the principal performance shaping factors (PSFs) that influence safe operations. The next step involves the use of the SHELLO model to group the main PSFs in elements named software, hardware, environment, liveware and organization. In the last phase, a relevant accident that occurred aboard a floating production storage and offloading (FPSO) vessel is analyzed. The allocation process of the factors that affect the operator's performance in risk assessment was developed through fuzzy logic and the ISO 17776 standard.     

采用遗传算法优化气体探测器布局策略研究

石油石化装置具有结构复杂且危险性高的特点,所加工物料多为易燃易爆有毒物质,且工艺单元之间集成度高,一旦发生泄漏若无法及时探测到则易形成气液积聚和火灾爆炸后果强化,装置拥塞度高使人员逃生困难。火气系统FGS作为安全关键系统,其中的气体探测网络如何快速可靠的实现对气体泄漏事件的探测显得尤为重要。已知探测时间,通过引入遗传算法利用其全局搜索的特点克服传统分支定界法的缺点,实现立体空间不同高度下设置探测网络达到场景全覆盖和缩短探测时间,同时求出探测时间附近的多组最优解,为探测器放置提供多种布置方案。通过与传统等间距探测器布置方案比较,从多种布置方案中选择更符合实际的最佳方案。通过海上浮式生产储油船的生产夹板气体探测案例,验证了所提方法的有效性。     

基于外加电流阴极保护法的FPSO保护方案

目的 确定目标FPSO主船体结构全寿命期下外加电流阴极保护系统中的最优参数。方法 采用计算机软件数值模拟的方法,建立目标FPSO主船体结构外加电流阴极保护模型,研究外加电流阴极保护系统中辅助阳极位置、数量以及输出电流对目标FPSO保护状态的影响。结果 分别在距离目标FPSO船尾57、127、191、267 m,吃水深度为5.3、5.7、5.7、5.2 m处的左、右两舷侧上对称布置共8个辅助阳极,各个辅助阳极初期释放电流分别为7、6、6、6 A,外加电流阴极保护系统输出总电流以34.6 A/a线性增加,可使得全寿命期下目标FPSO主船体结构水下部分处于完全保护状态。结论 采用计算机软件数值模拟计算可以快速得到外加电流阴极保护系统参数与目标FPSO保护状态之间的关系,进而可得到阴极保护最优参数,这为后续在目标FPSO上使用外加电流阴极保护系统确立最优参数提供了理论依据。     

A CFD based explosion risk analysis methodology using time varying release rates in dispersion simulations

A full probabilistic Explosion Risk Analysis (ERA) is commonly used to establish overpressure exceedance curves for offshore facilities. This involves modelling a large number of gas dispersion and explosion scenarios. Capturing the time dependant build up and decay of a flammable gas cloud size along with its shape and location are important parameters that can govern the results of an ERA. Dispersion simulations using Computational Fluid Dynamics (CFD) are generally carried out in detailed ERA studies to obtain these pieces of information. However, these dispersion simulations are typically modelled with constant release rates leading to steady state results. The basic assumption used here is that the flammable gas cloud build up rate from these constant release rate dispersion simulations would mimic the actual transient cloud build up rate from a time varying release rate. This assumption does not correctly capture the physical phenomena of transient gas releases and their subsequent dispersion and may lead to very conservative results. This in turn results in potential over design of facilities with implications on time, materials and cost of a project.In the current work, an ERA methodology is proposed that uses time varying release rates as an input in the CFD dispersion simulations to obtain the fully transient flammable gas cloud build-up and decay, while ensuring the total time required to perform the ERA study is also reduced. It was found that the proposed ERA methodology leads to improved accuracy in dispersion results, steeper overpressure exceedance curves and a significant reduction in the Design Accidental Load (DAL) values whilst still maintaining some conservatism and also reducing the total time required to perform an ERA study.     

泄漏油气燃爆灾害下FPSO结构响应分析

为评估FPSO泄漏油气燃爆事故中结构损伤风险,采用等效TNT法结合AUTODYN软件分析结构在爆炸冲击波下动态响应,分析其塑性、变形及应力分布,评估不同工况下结构损伤程度。结果表明,TNT起爆后冲击波高速传播,10ms时已覆盖工艺I区,经反射叠加耦合后破坏力增强;原油热处理器和电脱盐器发生失效和变形,生产甲板边缘位置受约束较小,发生较大变形,部分区域屈曲破坏;参与反应的油气越多,相同结构等效应力及变形越大,大应力、大变形区域分布越广;d=60mm时部分结构完全失效。