城市燃气输配系统网络结构抗毁性评估

为提高城市燃气输配系统网络结构抗毁性,针对其结构复杂,功能设备联系紧密,转换节点多等特点,建立网络模型,选取网络模型参数及抗毁性测度指标,对系统在不同攻击策略和模式下的抗毁性进行模拟仿真。研究结果表明:基于节点介数对城市燃气输配系统抗毁性影响最为显著;不同攻击策略下连续移除节点数目越少引起该系统抗毁性的变化越大;破坏初期进行维护是提高系统抗毁性最有效的途径。     

因果图和模糊综合风险评价在城市燃气输配系统的应用

针对复杂的城市燃气输配系统,利用因果图和模糊综合评价相结合的方法对其进行风险分析.因果图能找出影响城市燃气输配系统失效的因素,模糊综合评价则可在其基础上对风险量化.以某市的燃气输配系统为例描述了该方法的步骤.结果表明,因果图和模糊综合评价相结合的方法合理且易于工程应用.     

复杂网络理论下燃气管网节点重要性分析方法

为提高城市燃气管网重要节点的安全运行水平,基于复杂网络理论,构建城市燃气管网拓扑结构模型及评价指标体系;在不考虑管网方向性条件下,运用基于逼近理想解排序(TOPSIS)的多属性决策法,分析节点重要度;在考虑管网方向性条件下,采用PageRank算法分析节点重要性排序;综合分析管网的关键节点位置及重要性排序。结果表明:基于复杂网络理论的拓扑结构图能较清晰地显示管网节点所处位置;节点效率、网络节点中心性及网络方向性均为影响管网节点重要性的因素;管网流向对重要性高的节点有较大影响。     

基于贝叶斯网络的地震次生燃气管道泄漏事件链构建

地震次生燃气管道泄漏事件是导致地震灾害影响扩大的主要原因之一,为了解建 筑物内地震次生燃气管道泄漏事件的发展过程,参考国内外相关的文献和统计资料,确 定建筑物内地震次生燃气管道泄漏事件贝叶斯网络的节点变量和取值范围。根据节点变 量及其逻辑关联性构建贝叶斯网络结构图,通过对国内外研究数据的统计并结合专家经 验估算确定各节点变量的条件概率。利用贝叶斯网络工具计算建筑物属性和环境变量在 不同状态取值下建筑物遭受破坏、燃气泄漏、燃气扩散引发二次灾害等关键节点变量的 后验概率。通过实例分析得出,建筑结构和地震烈度是建筑物遭受破坏的主要影响因素 ,风速、大气稳定度对燃气扩散引发二次灾害有显著影响。     

基于复杂网络的燃气管道事故风险演化研究

为研究燃气管道事故各风险因素之间的复杂性,首先收集156份燃气管道事故案例,基于“4M理论”,从人的因素、设备设施因素、环境因素、管理因素4个方面确定了30个风险因素;运用Gephi软件构建燃气管道事故风险演化网络,并分析网络节点的度、平均路径长度、聚类系数和PR值,确定关键节点并对燃气管道安全管理提出建议。结果表明：应急处置不当、误操作、违章操作、管道腐蚀以及监督管理不足是导致燃气管道事故发生的关键风险因素,应控制这些关键风险因素,切断风险演化路径,防止燃气管道事故发生。     

灰色理论和DEMATEL在城市燃气管道风险评价中的运用

针对城市燃气管道风险评价时存在各因素相互作用会影响评价结果的问题，通过分析以往燃气事故发生原因、行业专家意见和相关规范标准，筛选整理出4项一级指标和19项二级指标，建立城市燃气管道风险评价指标体系。为保证城市燃气管道风险评价的准确性，引入灰色理论与决策试验法(Decision Making Trial and Evaluation Laboratory, DEMATEL)。首先，基于此方法分析各因素之间的影响关系；然后，得出各指标因素在评价指标体系中的重要程度；最后，对中心度进行归一化处理得到各影响因素的权重，结合模糊综合评价的方法对燃气管道进行风险评价。结果表明：阴极保护失效、管道运行年限、管道保护装置和人为破坏是导致燃气管道失效最重要的4个因素，燃气管道的风险等级为中等；分析结果与实际工程相吻合，证明该方法能够有效评估燃气管道风险。     

城市燃气供应系统Natech事件风险评估研究

为提高城市燃气供应系统抗灾能力和韧性水平，基于不同自然灾害诱发的城市燃气供应系统突发事件案例样本统计数据，探究城市燃气供应系统可能面临的典型自然灾害类别。首先，构建不同自然灾害诱发的城市燃气供应系统突发事件链，并转换为事故树模型和贝叶斯模型；然后，采用基本事件发生近似概率公式，对比分析不同模型的计算结果；最后，运用GeNIe 2.0软件逆向推理目标节点概率为100%时其他各节点的后验概率，总结关键节点，确定城市燃气供应系统可能面临的典型自然灾害。研究表明，城市燃气供应系统可能面临的典型自然灾害为暴雨、洪水、滑坡，且因考虑节点条件概率，贝叶斯模型计算结果更符合实际。     

基于模糊综合评价的城市燃气管网第三方破坏失效可能性研究

针对第三方破坏事故具有多样性、复杂性和不确定性等特点,建立城市燃气管网第三方破坏失效可能性评价模型。辨识出包括社会环境与公共关系、管道敷设状况、破坏与防控、管理与误操作以及自然环境等5类一级因素和19个二级因素,通过改进的层次分析法确定各级影响因素的权重,并运用多层次模糊综合评价法得出管道第三方破坏失效可能性的大小。以成都市某燃气管道为例进行验证分析,按照最大隶属度原则对评价结果进行处理。     

基于N-K模型的城市燃气管道失效可能性因素耦合分析

为分析多因素耦合作用对城市燃气管道失效可能性的影响，构建了基于复杂网络的N-K模型；应用轨迹交叉理论分析管道失效可能性因素的耦合作用机理；基于N-K模型对2011—2014年所发生的1 127起城市燃气管道事故进行耦合分析，计算不同耦合方式发生的概率和耦合值。结果表明:多因素耦合过程中，参与耦合的因素越多，管道失效的概率越大，但耦合发生的频率却随耦合因素的增加逐渐减少；环境因素和人为因素参与耦合时，管道失效的概率较大。     

保障城镇燃气场站设备安全

<正>城镇燃气场站作为城市天然气输配系统中的关键环节,具有储配、调峰、降压以及计量等重要功能。燃气场站的运行设备担负着向用户输送、供应燃气的任务,随着城镇燃气需求量的不断增加,燃气设备的负荷量也随之增加,设备是否能良好运行,检修维修是否及时安全,将影响到天然气输配系统乃至广大用户的安全。本文将在分析城镇燃气场站设     

基于贝叶斯网络的页岩气集输管道失效概率计算方法研究

页岩气集输管道运行压力和出砂量在生产过程中衰减显著，这导致管道失效概率不断变化，针对这一问题，采用贝叶斯网络方法，建立了页岩气集输管道失效概率动态计算模型。首先，分析页岩气气质特征、管道运行工况及失效原因，利用逻辑门的连接关系，建立了页岩气集输管道失效故障树；其次，基于贝叶斯网络与失效故障树的结构映射关系，将失效故障树转化成贝叶斯网络结构；然后，通过贝叶斯网络的参数学习，实现模型求解；最后，进行了实例应用。研究结果表明:该模型不仅可有效计算页岩气集输管道的失效概率，还能确定影响管道失效的关键风险因素，并且可通过调整节点的状态及概率分布，实现页岩气集输管道失效概率的更新。     

基于多因素耦合的井筒完整性风险评价

为了合理开展井筒完整性评价,提出合理的管理措施,综合考虑管柱力学、管柱腐蚀、管柱及附件密封、水泥环力学、地层以及油气井管理等关键节点及因素的相互耦合协同作用,分析多因素耦合协同作用对井筒完整性的影响。对于管柱力学等具有比较明确物理意义且可以量化的因素,采用定量分析评价;对于操作管理等难以量化的因素采用定性评价,对于腐蚀环境因素采用定量与定性相结合的方法进行评价;在定性及定量评价的基础之上,对关键节点进行风险概率和风险影响程度的划分及量化,再基于层次分析及风险矩阵的方法建立井筒完整性评价模型;基于模型编制了相应的计算程序,并对某高腐蚀性气井开展了井筒完整性评价。评价结果表明,在影响该井井筒完整性的风险因素中,高酸性气体腐蚀是造成该井井筒完整性失效的主要因素。     

Dynamic failure probability analysis of urban gas pipeline network

The gas pipeline network is an essential infrastructure for a smart city. It provides a much-needed energy source; however, it poses a significant risk to the community. Effective risk management assists in maintaining the operational safety of the network. The risk management of the network requires reliable dynamic failure probability analysis. This paper proposes a methodology of condition monitoring and dynamic failure probability analysis of urban gas pipeline network. The methodology begins with identifying key design and operational factors responsible for pipeline failure. Subsequently, a causation-based failure model is developed as the Bowtie model. The Bowtie model is transformed into a Bayesian network, which is analyzed using operational data. The key contributory factors of accident causation are monitored. The monitored data is used to analyze the updated failure probability of the network. The gas pipeline network's dynamic failure probability is combined with the potential consequences to assess the risk. The application of the approach is demonstrated in a section of the urban gas pipeline.     

储气库注采管柱螺纹失效动态风险评估*

为解决储气库注采管柱螺纹失效问题,识别注采管柱螺纹失效致因与后果,基于蝴蝶结和贝叶斯网络方法构建注采管柱螺纹动态失效风险分析模型,采用模糊集理论计算模型变量先验概率,并评估注采管柱失效后果概率,从而推断注采管柱螺纹失效关键致因因素;引入先兆数据,评估注采管柱螺纹动态失效风险态势。结果表明:气体中携带固体颗粒、上螺纹速度过快、注采温度高、地层断裂等13个因素对螺纹失效风险影响较大;螺纹失效概率逐渐增大,螺纹失效后果也越来越严重,需要监控螺纹失效关键致因以降低螺纹失效的风险。     

基于HCNAM-BN的化工过程爆炸事故致因链分析

为了从源头上预防化工过程爆炸事故,依据风险耦合理论,探讨了各风险因子非线性耦合演化为爆炸事故的机理,构建了层次耦合网络分析模型（HCNAM）;从多因素风险耦合角度分析了国内外44起典型化工过程爆炸事故,统计了各风险因子之间的耦合概率并进行了耦合致因重要度分级;采用耦合概率与二态分布相结合的条件概率分布,将层次耦合网络分析模型转化为贝叶斯网络,并对氯乙烯单体槽爆炸性混合气体爆炸事故进行了应用研究。结果表明:91种双因子耦合风险状态中,47种呈现弱耦合致因特性;7种因子双耦合形成风险的概率较大;基于HCNAM-BN模型分析事故,可有效辨识事故最可能致因因素,获取各事故致因链的发生概率并确定事故网络关键节点。     

Simulation and application of a disaster spread model in Chemical Disaster Network

In the research field of chemical safety, the computer-aided simulation for occurrence and process of disasters has become a major trend in current research, in which the establishment of evolution system for chemical multi disasters is the key point. In the paper, the study lays emphasis on the simulation and application of a spread model for chemical multi disasters. After establishing a disaster network, we defined microcosmic elements of spread model specifically. Combined with guideline of chemical disaster (e.g. guideline of heat flux for damages or injure, guideline of evaluation for buildings based explosion and overpressure, and guideline of evaluation for human exposure to toxic gases), the weight of impact can be computed using new comprehensive algorithms. Simultaneously, the paper also uses an approach on simulating multiple failure events to describe random factors of triggering disasters. At last, the experimental case of alkyl aluminum leakage in a polypropylene plant shows the result of simulation with table of 5 major series of disasters and distribution diagram of nodes (disasters) in disaster network. This proves the validity and practicability of the simulation system in the establishment and feedback of contingency plan of large-scale petrochemical enterprises.     

Using an expanded Safety Failure Event Network to analyze railway dangerous goods transportation system risk-accident

In order to improve the reliability and safety of railway dangerous goods transportation system (RDGTS), and prevent the similar accidents happened again, an easier operated, dynamic, systemic and quantitative approach called expanded Safety Failure Event Network (SFEN) is proposed to analyze the past typical RDGTS accidents. The expanded SFEN focuses on transfer the traditional safety occurrence process into a visible Accident Analysis Network (AAN) platform. To improve the previous SFEN approach, the risk factors categories are expanded including Human actions, Technical failure, Nature of transported goods, Environment factors, Management failure and External factors of the system. An AAN is established by using the risk factors as the nodes and using the interactions among these risk factors as the edges, the RDGTS risk analysis problem is transferred into a quantitative network structure analysis problem from a network perspective. After that, based on the AAN, TouchGraph and NetMiner are applied to calculate and rank the centrality degree of each sub-risk factor (or sub-heading) in a network. A RDGTS accident happened in 2001 is analyzed, the results show that TouchGraph and NetMiner can present the same interactions and importance of sub-risk factors (or sub-headings) through visible circle images in the platform, NetMiner is more digital because the results can be presented as the centrality degree values. The greatest contributed sub-risk factors are Equipment maintenance failure and Railway inspection agency failure, followed by cargo packaging problems, illegal entrainment problem. Misbehaves of the freight inspector with centrality degree 0.523810 shows that this sub-heading has the greatest contribution to the accident.     

Reliability assessment of ultra-deep oil and gas wellbore casing using data statistics and numerical simulations

Ultra-deep oil and gas wells have become a new development trend in onshore oil and gas exploitation. However, Ultra-deep oil and gas wellbore casing is with high failure risk due to the harsh environment. It is essential to evaluate the reliability of wellbore casing. This paper assesses the operational reliability of wellbore casing using data statistics and numerical simulation. Firstly, the theoretical model for reliability analysis of wellbore casing is established, and the variables in the model are determined, including rock mechanics, cement ring, and casing string strength factors. Subsequently, considering the random distribution of model variables, many statistics and analyses are performed to determine the distribution parameters of the model variables. Eventually, Monte Carlo based numerical simulations are carried out to obtain the residual strength distribution and the reliability of wellbore casing. The production casing in the ultra-deep well with a depth of 6.5 km in China as an industrial case is used to illustrate the present study. It is observed that this study can be useful to guide a more accurate assessment of the reliability of ultra-deep wellbore casing.     

基于贝叶斯网络的城市地下燃气管网动态风险分析

为研究城市燃气管网风险的动态性,针对传统风险分析方法的局限性,提出基于贝叶斯网络的燃气管网动态风险分析方法。构建燃气管网失效蝴蝶结模型并将其转化为贝叶斯网络模型;在事故发生状态下更新事件失效概率,识别出关键因素;根据异常事件数据和贝叶斯理论,对基本事件失效概率进行实时动态改变;随之更新管网失效及各后果发生的概率,从而实现管网的动态风险分析。研究结果表明:该方法克服了传统风险分析方法的不足,可动态反映燃气管网失效和事故后果发生概率随时间变化的特征,能够为城市地下燃气管网的风险分析与事故预防提供参考。     

基于风险的城市埋地燃气管道安全评价模型及应用

城市埋地燃气管道一旦失效会产生泄漏,甚至引发火灾爆炸等事故,造成人员伤亡和财产损失等严重后果,影响社会稳定,因此其安全运行十分重要。由于城市地下环境的复杂性,使得埋地燃气管道失效的因素多种多样,且具有模糊性;由于城市地面状况各异,所以构成失效后果的因素也具有不确定性。文章以某市在役燃气管道为例,使用模糊数学语言表达了埋地燃气管道的失效可能性和失效后果,采用模糊综合评价模型对燃气管道的失效可能性和失效后果进行了评价,并以美国石油协会(API)风险矩阵表征了埋地燃气管道的风险等级,得到不同管道单元的风险级别和管道单元数,根据不同的风险等级采取不同的策略或措施,完善管道的完整性管理,降低管道的使用风险,确保城市燃气管网的正常安全运行。