The measurement of health and safety performance is an important requirement but most performance metrics are lagging indicators, measuring lost time incidents, dangerous occurrences etc. The challenge is to develop metrics that can be applied at the design stage. It is widely recognised that most accidents are influenced by the design stage, and many can be directly attributable to deficiencies in design. This paper is concerned with a design capability maturity model’, which is complementary to the design safety performance indicator model developed to apply to the design process itself. It has been developed to measure the capability of an organisation to design a safe installation, and is based on five maturity levels, ranging from level 1 (initial or learner approach) to optimised or best practice at level 5. This maturity model was originally developed for the software industry and has now been applied to offshore safety. A similar maturity model for quality assurance is now incorporated in the latest version of ISO 9004. Eleven characteristics associated with safety have been identified, in three main groups representing formal safety demonstration, safety implementation and longer term investment in safety. A maturity level is assigned to each of these characteristics and the profile produced reflects the organisation’s overall maturity in design for safety. An important aspect of the model is that it enables an organisation to establish its current level of maturity for each of the characteristics and to identify what steps are necessary to enable the organisation to progress to a higher level. The model can be used as a self assessment tool or applied through an external independent body to the different organisations involved in design (contractor’s design team, duty holder’s team etc).
Many North Sea installations are now at or beyond their original design lives, and this raises questions about the demonstration of the safety of the structures to remain in service. Whereas most of the topsides equipment is accessible for inspection and maintenance, and deteriorating parts can be repaired and replaced, such IRM is extremely expensive for the underwater structure. Indeed, widespread inspection of structures cannot realistically be undertaken for both cost and safety reasons. The North Sea concerns on managing life extension affect both fixed platforms and semi-submersibles, and these are also reflected in many other parts of the world including the Gulf of Mexico and the Far East. The management of life extension requires an assessment of both the original design requirements, changes in standards and loading conditions and the current state of the structure. ISO 19902 includes a new section on reassessment, which has been developed with international input (including the authors). A methodology has been developed by Cranfield University, in conjunction with Galbraith Consulting and Sauf Consulting, to assess how well operators and their contractors apply their knowledge of individual structures, corporate requirements, behaviour of materials and worldwide experience in determining inspection and repair requirements for an individual structure. The work was funded by the Norwegian Petroleum Safety Authority (PSA), as they needed a tool to provide a framework for their structural audits; however the methodology can be used by operators as a self assessment tool. An assessment determines the "maturity" of the operators' decision making in a number of different areas - higher maturity requires greater understanding and investment in planning, but the resulting maintenance should be both cheaper and safer, particularly for life extension purposes. The paper describes the main issues in managing life extension, including evolution and operation of the above methodology. Introduction In many offshore locations world-wide oil & gas installations are now in a life extension stage, having exceeded their original design lives. Many of these, particularly the major platforms in the Northern North Sea, and similar platforms elsewhere, are expected to remain operational for the production of oil and gas for the foreseeable future. There are several reasons why a platform's life might be extended and these include: - reservoir proving more extensive or productive than originally envisaged; - enhanced production techniques (e.g. hydraulic fractures) allowing a higher percentage of the hydrocarbons in place to be extracted; - long reach drilling techniques allowing more distant accumulations to become economically viable; - improved seismic techniques providing greater detail on where reachable accumulations can be found (e.g. deeper accumulations); - being used to function as an export hub, either by being at the end of a trunk pipeline or storage and offloading facilities; - provision of processing capability for nearby subsea or minimum facility platforms; - the very high costs of decommissioning a fixed northern North Sea platform can skew the economics of operating at near-end-of-life such that a marginal return or an operating loss becomes both likely and acceptable. Ageing processes can clearly affect the integrity of an installation and the demonstration of adequate performance beyond its original design life is thus a necessary requirement. This frequently entails a formal demonstration to a certification or verification body or to a regulator that there is sufficient integrity to continue safe operation throughout the extended platform life. There are numerous ageing and degradation mechanisms which affect different areas of the offshore infrastructure and some of these are discussed below.
Many offshore installations in the North Sea have now exceeded their original design life and are in a life extension phase. A Framework of six processes has been developed for the management of ageing of Safety Critical Elements (SCEs) in offshore installations. The processes include an analysis of the effect of ageing modes on SCE performance. Examples of performance indicators for typical SCEs are proposed based on how their condition and performance as may be affected by physical deterioration and other effects of ageing. Indicators for calibrating the maturity and effectiveness of the management processes are also suggested.
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