Application of dynamic risk analysis in offshore drilling processes

Process safety is the common global language used to communicate the strategies of hazard identification, risk assessment and safety management. Process safety is identified as an integral part of process development and focuses on preventing and mitigating major process accidents such as fires, explosions, and toxic releases in process industries. Accident probability estimation is the most vital step to all quantitative risk assessment methods. Drilling process for oil is a hazardous operation and hence safety is one of the major concerns and is often measured in terms of risk. Dynamic risk assessment method is meant to reassess risk in terms of updating initial failure probabilities of events and safety barriers, as new information are made available during a specific operation. In this study, a Bayesian network model is developed to represent a well kick scenario. The concept of dynamic environment is incorporated by feeding the real-time failure probability values (observed at different time intervals) of safety barriers to the Bayesian network in order to obtain the corresponding time-dependent variations in kick consequences. This study reveals the importance of real-time monitoring of safety barrier performances and quantitatively shows the effect of deterioration of barrier performance on kick consequence probabilities. The Macondo blowout incident is used to demonstrate how early warnings in barrier probability variations could have been observed and adequately managed to prevent escalation to severe consequences.     

危险工业设施周边土地利用规划研究

由于工业设施的存在,其周边区域常常受到潜在工业事故的威胁,为了减小这种风险,必须对这些区域进行合理的土地利用规划。借鉴欧洲研究者的研究方法,利用基于后果的风险评价方法确定不同破坏分区的边界,并将不同土地利用类型的脆弱等级引入土地利用规划,结合二者的结果,依据决策矩阵得到规划决策意见。通过将上述方法应用在某拟建的LPG中转站周边区域,以丙烷泄漏引起的沸腾液体蒸气爆炸为例,将风险分析和决策结果显示在地理信息系统上。案例分析表明该设施对周边区域影响较大,需要对其进行重新选址。     

Dynamic Procedure for Atypical Scenarios Identification (DyPASI): A new systematic HAZID tool

The availability of a hazard identification methodology based on early warnings is a crucial factor in the identification of emerging risks. In the present study, a specific method named Dynamic Procedure for Atypical Scenarios Identification (DyPASI) was conceived as a development of bow-tie identification techniques. The main aim of the methodology is to provide a comprehensive hazard identification of the industrial process analysed, joined to a process of continuous improvement of the results of the assessment. DyPASI is a method for the continuous systematization of information from early signals of risk related to past events. The technique provides a support to the identification and assessment of atypical potential accident scenarios related to the substances, the equipment and the site considered, capturing available early warnings or risk notions. DyPASI features as a tool to support emerging risk management process, having the potentiality to contribute to an integrated approach aimed at breaking “vicious circles”, helping to trigger a gradual process of identification and assimilation of previously unrecognised atypical scenarios.     

基于FTA与SPA方法的湿法成型硫磺料仓安全分析与评价研究

为了控制湿法成型硫磺料仓风险,评估硫磺料仓安全状态,采用事故树方法分析了硫磺料仓发生火灾爆炸事故的原因,并利用最小割集和最小径集分析了事故的可能途径,确定了最佳控制方案为控制可燃粉尘和气体的聚集。针对硫磺料仓安全状态影响因素的不确定性和动态性的特点,将多元联系数集对分析法引入硫磺料仓危险性评价中,建立了料仓危险性评价指标体系,综合判断了料仓危险性态势。评价结果与现场实际情况较符合,为湿法成型硫磺料仓的安全评价工作提供了思路,为其风险控制措施的制定提供了参考。     

基于改进云模型-IAHP的涉爆粉尘企业安全风险评估

为了评估涉爆粉尘企业安全风险,克服传统评估过程中数据随机性和模糊性的缺陷,建立了基于云理论和区间层次分析法(IAHP)的涉爆粉尘企业安全风险评估模型。针对粉尘爆炸事故的特点构建涉爆粉尘企业安全风险指标体系,使用云理论为主客观指标赋值,采用IAHP确定各指标权重并引入可能度修正权重结果,基于改进的云合并算法整合计算结果,以综合评估企业粉尘爆炸风险,并将该模型应用于某金属加工企业。研究结果表明:该企业的粉尘爆炸风险处于一般水平,其工人安全意识薄弱、防尘及防爆措施不完善、生产布局和管理不规范等原因导致了该企业的风险,该模型评估结果与实际情况相符,为提高企业安全管理水平提供依据。     

城市重大危险源管理中的GIS应用研究

在阐述重大危险源管理要求的基础上,研究地理信息系统在重大危险源信息描述、数据管理、风险评价和风险绘制、事故预警以及事故应急救援中的应用。通过地理信息系统描述和管理重大危险源,方便地表示和查询城市各重大危险源的地理位置;利用GIS进行风险评价和风险地图绘制,评估和表示出城市不同区域和地段的相对风险大小,便于城市发展规划;利用GIS进行事故预警,可及时发现和确定重大危险源事故隐患位置,并通过采取措施消除事故在萌芽状态;利用GIS辅助应急救援,有助于分析事故的发展趋势、影响范围和寻求事故救援的最佳路径等其他重大救援决策。     

Risk assessment of chemical process considering dynamic probability of near misses based on Bayesian theory and event tree analysis

With the development of modern automatic control systems, chemical accidents are of low frequency in most chemical plants, but once an accident happens, it often causes serious consequences. Near-misses are the precursor of accidents. As the process progresses, near misses caused by abnormal fluctuation of process variables may eventually lead to accidents. However, variables that may lead to serious consequences in the production process cannot update the risk in the life cycle of the process by traditional risk assessment methods, which do not pay enough attention to the near misses. Therefore, this paper proposed a new method based on Bayesian theory to dynamically update the probability of key variables associated with process failure risk and obtain the risk change of the near-misses. This article outlines the proposed approach and uses a chemical process of styrene production to demonstrate the application. In this chemical process, the key variables include flow rate, liquid level, pressure and temperature. In order to study the dynamic risk of the chemical process with consideration of near misses, according to the accumulated data of process variables, firstly the abnormal probability of the variables and the failure rate of safety systems associated with the variables were updated with time based on Bayesian theory. On the basis of the dynamic probability of key process variables, an event tree of possible consequences caused by variable anomalies was established. From the logical relationship of the event tree, the probability of different consequences can be obtained. The results show that the proposed risk assessment method based on Bayesian theory can overcome the shortcomings of traditional analysis methods. It shows the dynamic characteristics of the probability of different near misses, and achieves the dynamic risk analysis of chemical process accidents.     

重大事故动力学演化

为进一步研究重大事故发生演化机理，在对典型重特大事故比较研究的基础上，应用系统动力学理论分析重大事故孕育、发生、发展和激变的动力学特征，认识重大事故行为过程及其主要影响因素，探讨重大事故闭环反馈系统的调控规律。作者建议应用系统动力学理论与方法建立决策实验室，以提高对重大事故风险控制水平。     

Scenario derivation and consequence evaluation of dust explosion accident based on dynamic Bayesian network

In order to clarify the correlation between the evolution path of dust explosion accidents and emergency decision-making, and to accurately predict the disaster damage levels of various disaster bearing bodies. This paper extracts 56 key scenario elements from four aspects, namely state, answer, goal and environment, based on the analysis of typical dust explosion accident cases. At the same time, a general scenario evolution path of dust explosion accident is constructed. Using fuzzy number set theory and dynamic Bayes joint probability model, the accurate solution of scenario state probability was realized. With the help of accident cases and dynamic Bayes approach, the dust explosion consequence prediction index system and evaluation criteria were constructed, covering factors such as dust explosion intensity, casualties, direct economic losses, equipment damage, building damage, environmental damage and other factors. A polyethylene wax dust explosion accident in a city of China was used to verify the dust explosion accident scenario evolution model and consequences prediction model. The predicted results were in good agreement with the actual damage of various carriers of the accident, which indicated that the model could be used for dust explosion accident prediction and disaster loss prediction. The research results provided reference and technical support for the prediction of dust explosion accident evolution direction, emergency aid measures decision and deployment, disaster damage prediction and evaluation.     

粉尘爆炸事故模式及其预防研究

随着粉体工业的发展,粉尘爆炸发生的危险性也随之增大。为了探讨粉尘爆炸发生的规律,笔者对粉尘爆炸发生的点火源类型、事故原因进行了统计、排序;在对已发生的典型的粉尘爆炸事故分析的基础上,总结、归纳了影响粉尘爆炸发生的,诸如粉尘自身的可燃性、粉尘所处的状态、粉尘所处的外部环境等因素;提炼出了7种粉尘爆炸事故模式,并对各种模式下粉尘爆炸发生的条件、机理进行了初步研究分析,然后提出了相应的事故预防措施。笔者所研究的成果,对粉体工业的安全生产具有实际的指导作用,对今后防灾决策的深入研究也具有一定的参考价值。     

On the development of a new hybrid risk assessment process using occupational accidents’ data: Application on the Greek Public Electric Power Provider

The occupational accidents have a major impact upon human integrity and also bring about high costs for the social health and insurance system of a country. In addition, risk analysis is an essential process for the safety policy of a company, having as main aim the effacement of any potential of damage in a productive procedure, while the quantified risk evaluation is the most crucial part of the whole procedure of assessing hazards in the work. The main goal of this study is double: a) the development and presentation of a new hybrid risk assessment process (HRAP) and b) the application of HRAP in the Greek Public Power Corporation (PPC) (the unique electric power provider and the largest industry in Greece), by using occupational accidents that have been recorded, during the 12-year period of 1993-2004. The new process consists of four distinct phases a) the hazard sources’ identification phase, b) the risk consideration phase, c) the risk-evaluation phase, and d) the phase of the risk assessment and safety-related decision making. The results show that in some cases the risk value has been calculated in PPC to be higher than 500 (in the risk rating of 0-1000), which imposes the taking of suppressive measures for abolishing the danger source, while the fatal accident frequency rate (per 10⁸ man-hrs) is FAFR ≅ 2.4.     

基于WebGIS的危险化学品污染事故应急决策支持系统

通过对危险化学品污染事故危害性的分析,指出环境污染事故应急处置的紧迫性和必要性;给出了事故应急决策支持机制,采用案例推理与规则推理相结合的推理技术来实现事故应急方案的自动生成;借助于WebGIS技术,建立起集成污染事故风险评估与预警、监测分析、快速处理等多项技术的系统平台;该系统创建了集成空间信息、属性信息和文档信息的污染应急决策数据库,提供了环境污染危险的评估技术,建立了环境污染的扩散模型,实现了环境污染事故应急监测与处置技术的集成应用。实践证明,该系统能为危险化学品污染事故的应急处理提供及时、有效的决策支持。     

Application of domino effect quantitative risk assessment to an extended industrial area

Escalation of primary accidental scenarios triggering a “domino effect” have caused extremely severe accidental events in the chemical and process industry. The identification of possible escalation events is required in the safety assessment of sites where relevant quantities of hazardous substances are stored or handled. In the European Union, “Seveso-II” Directive requires the assessment of on-site and off-site possible escalation scenarios in sites falling under the obligations of the Directive. In the present study, a methodology developed for the quantitative assessment of risk due to domino effect was applied to the analysis of an extended industrial area. Recently developed equipment damage probability models were applied for the identification of the final scenarios and for escalation probability assessment. The domino package of the Aripar-GIS software was used for risk recomposition. The results evidence that quantitative risk assessment of escalation hazard is of fundamental importance in order to identify critical equipment and to address prevention and protection actions.     

Integrated dynamic risk assessment of buried gas pipeline leakages in urban areas

In urban areas, buried gas pipeline leakages could potentially cause numerous casualties and massive damage. Traditional static analysis and dynamic probability-based quantitative risk assessment (QRA) methods have been widely used in various industries. However, dynamic QRA methods combined with probability and consequence are rarely used to evaluate gas pipelines buried in urban areas. Therefore, an integrated dynamic risk assessment approach was proposed. First, a failure rate calculation of buried gas pipelines was performed, where the corrosion failure rate dependent on time was calculated by integrating the subset simulation method. The relationship between failure probability and failure rate was considered, and a mechanical analysis model considering the corrosion growth model and multiple loads was used. The time-independent failure rates were calculated by the modification factor methods. Next, the overall evolution process from pipeline failures to accidents was proposed, with the accident rates subsequently updated. Then, the consequences of buried gas pipeline accidents corresponding to the accident types in the evolution process were modeled and analyzed. Finally, based on the above research, dynamic calculation and assessment methods for evaluating individual and social risks were established, and an overall application example was provided to demonstrate the capacity of the proposed approach. A reliable and practical theoretical basis and supporting information are provided for the integrity and emergency management of buried gas pipelines in urban areas, considering actual operational conditions.     

基于改进LEC法的危化企业静电点燃危险评价

危化企业爆炸性危险环境下由静电放电引发的火灾爆炸时有发生,针对这一问题分析了危化企业气体、液体、固体、粉体及人体在不同生产工艺过程中静电电荷来源以及可能的静电放电形式。综合考虑静电点燃源形成可能性、爆炸性环境形成可能性、监控与控制措施有效性以及静电事故后果严重度,构建了基于改进LEC法的静电点燃危险评价方法,该评价方法能实现对危化企业静电点燃源危害的量化评估与分级。应用该方法对某加油站进行静电点燃危险评价,并根据评价结果提出了预防改进措施。     

Dynamic-risk-informed safety barrier management: An application to cost-effective barrier optimization based on data from multiple sources

An integrated approach for performance assessment and management of safety barriers in a systemic manner is needed concerning the prevention and mitigation of major accidents in chemical process industries. Particularly, the effects of safety barriers on system risk reduction should be assessed in a dynamic manner to support the decision-making on safety barrier establishments and improvements. A simulation approach, named Simulink-based Safety Barrier Modeling (SSBM), is proposed in this paper to conduct dynamic risk assessment of chemical facilities with the consideration of the degradation of safety barriers. The main functional features of the SSBM include i) the basic model structures of SSBM can be determined based on bow-tie diagrams, ii) multiple data (periodic proof test data, continuous condition-monitoring data, and accident precursor data) may be combined to update barrier failure probabilities and initiating event probabilities, iii) SSBM is able to handle uncertainty propagation in probabilistic risk assessment by using Monte Carlo simulations, and iv) cost-effectiveness analysis (CEA) and optimization algorithms are integrated to support the decision-making on safety barrier establishments and improvements. An illustrative case study is demonstrated to show the procedures of applying the SSBM on dynamic risk-informed safety barrier management and validate the feasibility of implementing the SSBM for cost-effective safety barrier optimization.     

PLR事故隐患分级法在上海市化工企业中的应用

PLR事故隐患分级法针对火灾、爆炸、毒物泄漏重大事故类型 ,根据事故隐患评价的基本原理 ,结合上海市事故发生及隐患普查现状 ,提出了上海市“重大事故隐患”的定义和辨识方法 ,确定了事故隐患易发性(P)、事故导致损失程度 (L)和事故后果影响范围 (R0 .5)三项评价指标 ,并将P ,L ,R三项指标组合成“PLR事故隐患分级评价表” ,由PLR事故隐患分级评价表得出事故隐患分级结果。新方法通过在上海市典型化工企业的试点应用 ,验证了PLR事故隐患分级法在化工企业中的可操作性和有效性 ,为上海市重大事故隐患的辨识、评价和整改工作提供了科学的管理方法     

煤矿危险源风险预警与控制的研究

根据现代安全管理的理论与方法,结合煤矿人-机-环境特点和不同煤矿事故的发生机理,对煤矿危险源风险预警和控制的基本理论和方法进行了探讨,提出了基于危险源的煤矿风险预警与控制的一般流程,给出煤矿危险源辨识、风险评价、监控和预警的方法,为煤矿安全管理信息系统提供理论基础。     

Modelling of BP Texas City refinery accident using dynamic risk assessment approach

Process industries involve handling of hazardous substances which on release may potentially cause catastrophic consequences in terms of assets lost, human fatalities or injuries and loss of public confidence of the company. In spite of using endless end-of-the-pipe safety systems, tragic accidents such as BP Texas City refinery still occur. One of the main reasons of such rare but catastrophic events is lack of effective monitoring and modelling approaches that provide early warnings and help to prevent such event. To develop a predictive model one has to rely on past occurrence data, as such events are rare, enough data are usually not available to better understand and model such behavior. In such situations, it is advisable to use near misses and incident data to predict system performance and estimate accident likelihood. This paper is an attempt to demonstrate testing and validation of one such approach, dynamic risk assessment, using data from the BP Texas City refinery incident.Dynamic risk assessment is a novel approach which integrates Bayesian failure updating mechanism with the consequence assessment. The implementation of this methodology to the BP Texas City incident proves that the approach has the ability to learn from near misses, incident, past accidents and predict event occurrence likelihood in the next time interval.     

Dynamic Inherently Safer Modifications: Metric development and its validation for fire and explosion prevention

Of the numerous inherent safety assessment tools, a dynamic metric capable of investigating and incorporating the temporal risk evolution when conducting Inherently Safer Modifications (ISMs) is yet to be established. To this end, this work developed a Dynamic Inherent Safety Metric (DISM) and validated its functionality and viability through a case study. Firstly, the Information-Flow-based Accident-causing Model (IFAM) was adapted to construct the topology of Bayesian Networks (BN). Then, Bayesian deductive reasoning was executed to do crucial risk identification by ranking posterior probabilities. Finally, risk-based ISMs were performed to address the relatively contributing risk factors. The case study results show that the fire and explosion risk decreased by approximately a third after implementing ISMs, thus demonstrating that the modified processing scenario could be inherently safer than the original processing scenario. The newly developed inherent safety metric (i.e., DISM) can assist in temporal risk identification and assessment, and it is expected to function as a novel assessment tool for measuring and comparing the inherent safeness before and after implementing ISMs with simultaneous considerations on the time-varying risk factors.