Stein Hauge

Integrated Barrier Analysis in Operational Risk Assessment in Offshore Petroleum Operations

The BORA project is aimed at detailed and quantitative modeling of barrier performance, including barriers to prevent occurrence of initiating events, and barriers to avoid or reduce consequences. Challenges related to the modeling are reviewed, and some solutions are suggested.

Common cause failures in safety-instrumented systems: Using field experience from the petroleum industry

Safety instrumented systems often employ redundancy to enhance reliability, but the intended effect may be reduced when common cause failures are taken into account. It is often assumed that a certain fraction of component failures will occur close in time, due to a shared cause. Unfortunately, few attempts have been made to systematically investigate field experience on common cause failures, with the exception of the nuclear industry which has been in the forefront of research in this area. This paper presents selected results from a research project carried out in the Norwegian oil and gas industry to collect and analyze reported failures. This includes the presentation and derivation of generic (i.e. industry average) values of beta-factors for typical components in the oil and gas industry, and the demonstration of how failure data may be used to construct checklists for updating the value of beta in operation. The results are based on a review of some 12.000 maintenance notifications from six different onshore and offshore petroleum facilities. It is found that the new beta-values are higher than what is seen in many data sources, and some possible explanations are discussed.

Reflections on the Concept of Safety Barriers

This paper deals with the concept of safety barriers and contains a presentation and discussion of different aspects of the term. Based on findings from an analysis of the containment barrier function on oil and gas production platforms, some specific considerations concerning safety barriers are also presented.

Human and Organizational Contributions to Safety Defences in Offshore Oil Production

Offshore petroleum production involves several major hazards. In the tightly coupled production systems, incidents such as gas releases can quickly escalate to major accidents. The industry meets this challenge by introducing various safety defences such as firewalls, emergency shutdown systems, and work permit systems to make the platforms fault tolerant, i.e., to ensure that technical and human failures will not result in incidents or accidents. In high-risk industries the attitude to humans as part of the safety defences has traditionally been sceptic. Humans are perceived to be error prone, and it has generally been seen as desirable to minimize and control humans’ contribution to the extent possible using automation and operating procedures, respectively. In this paper we will argue that humans are essential as part of the safety defences at petroleum installations. Humans’ contributions are of particular importance in situations where the tasks required to defend safety cannot be automated, i.e. reliably accounted for in algorithms, because humans furnish required flexibility into the safety defences. To contribute positively to safety, i.e., in ways that lead to a reduction in the risk level, individuals and work groups need to be supported by appropriate organizational means, such as adequate knowledge, competence, resources, and tools. For this reason, we will refer to defences in which humans are allocated tasks to contribute to plant safety as human and organizational defences. In the paper we will outline three ways in which human and organizational defences are applied at petroleum installations, and discuss what kind of means that are needed to support these types of defences. The paper is based on the outcome of the first part of a research activity on fault tolerance, barriers and resilience [1, 2], which is performed within the framework of the project “HSE Petroleum: Change — Organization — Technology [3]. The issues presented in this paper will be addressed in more details in the following parts of this project.

Barrier Change Analysis Method

“Change is the mother of twins — progress and trouble” [1]. In some areas of operation, change is the very mechanism for survival. In the exploitation of non-renewable resources, like oil and gas, the operations and maintenance costs will at some point exceed the revenues. In order to maximize the overall exploitation of the reservoir, the cost side has to be reduced and the key word is“change” — technical, operational, and organizational changes. In particular remote operation and de-manning are relevant measures to extend the tail production phase. Another topical issue is major replacements of old equipment, e. g., the safety and automation system, due to lack of spare parts and problems in maintaining sufficient competence on yesterday’s systems. The central issue then, from a safety perspective, is how to analyze such complex changes with respect to their effect on the risk of accidents (the“trouble” part of change).