Quantitative & Qualitative Risk Analyses - The Safety of Offshore Platforms
Authors: Bea Robert G. 
Published: October 2008

Two primary methods have been used in performing safety audits of platforms:qualitative methods such as Hazop (Hazard and operability analyses) and FEMA (Failure Modes and Effects Analyses) and,quantitative methods such as QRA (Quantified Risk Analyses) and PRA (Probabilistic Risk Analyses).

A third method, identified in this paper as Safety Indexing Methods (SIM), has been developed and is being applied to offshore platforms. This paper discusses experience ith applications of these methods in development of safety audits on offshore platforms. The pros and cons of these alternative methods are discussed.

Results of the experiences summarized in this paper highlight the potential complimentary nature of the three assessment methods. These experiences indicate that it is critical that the fundamental objective of the applications of these methods be kept in clear view. h is contended that the fundamental objective of the applications should be to develop improvements in the safety of offshore platform operations and not to produce elegant analytical constructs. The most essential ingredient in such improvements is the integration of the experience, insights, and judgment of those that have direct and daily responsibilities for field operations.

Selection of an assessment and auditing process must take into account the skills and knowledge of these people. Any safety audit process that does not account for implementation in and by the field rarely is beneficial to safety. Whatever method is used should facilitate interactions with the people in the field, and should result in the empowerment of those in the field.

An important objective of this work is to help enhance platform safety while at the same time enhancing the long erm profitability of the operation: ‘Safety can be good business.’] Experience indicates that some safety related activities should be disarded and more effective and efficient methods adopted. Thus, improvements in how safety is achieved can lx realized without increasing costs. Profitability is required because without this profitability the resources will not be available to improve safety. There needs to be an equitable balance between adequate safety and sufficient profitability.

Introduction

Experience has amply demonstrated that the major problems associated with the safety of offshore structures generally are not associated with the structures or the equipment onboard these structures. They are associated with Human and Organization Factors (HOF) that develop during the design, construction, operation, and maintenance of the structures.2

Table 1 summarizes observations bawl on results from a study of several hundred well documented cases involving low probability, high-consequence (LP/HC) platform accidents, 3 These observations indicate that the primary concerns for platform safety should be centered in equipment and facilities involving interactions with human and organization factors during operations and maintenance that can result in blowouts, explosions, and /or fires. While individuals can be blamed for initiating accidents, the prevalent contributing and compounding factors associated with the initiation and escalation of accidents are related to organizations.