The current risk management regulatory approach for the Norwegian offshore petroleum industry came into effect in 2001, but relatively few new installations were decided after 2001 for development until quite recently. Since 2012, there have been several new installations that are being planned or have reached front-end engineering design (FEED) or engineering phases. This paper considers the risk management approach in the pre-FEED phase and builds on some case studies selected from the most recent cases. The main principles for major hazard risk management in this phase are summarized, and the experience from the case studies is discussed with respect to establishing how well they have functioned. It is demonstrated that the risk reduction approach is not as effective as it could have been. The paper proposes some improvements to the regulatory approach to risk reduction in the pre-FEED phase in order to make improvements to the management of major hazard risk and to achieve installation concepts that are more robust in relation to changes and additional requirements during the field lifetime.

Production and storage tankers are being evaluated extensively for development of marginal oil and gas fields in the North Sea. The main safety aspects of these vessels are discussed, based on a number of quantitative risk assessments for these vessel concepts. These studies have confirmed the importance of several important safety features, such as a fire-protected, enclosed escape way along one of the sides of the ship. Other important safety features include weather-vaning capability as a function of the turret location, location and configuration of the flare system, protection of cargo tanks by inert gas blanketing, as well as procedures for strict control of tank intervention. The results, show that the production and storage vessels have favorable safety characteristics, and that these concepts represent an acceptable and feasible solution for the marginal fields.

The full life cycle approach to risk acceptance is proposed as the basis for establishing of acceptance criteria for the temporary phases, i.e., onshore and offshore construction as well as installation. The background for such criteria is discussed, as well as evaluations that may be used to formulate risk acceptance criteria in the construction and installation phases. The criteria are focused on personnel safety. Environmental spill protection and protection of assets are also addressed, but less extensively. FAR or AIR values are used to express tolerable personnel safety, whereas the acceptability of exposure of the investment is expressed in terms of acceptable probabilities of accidents with significant effect on the project time schedule, i.e., the possibility to delay significantly the start-up of the production phase. The approach is based on an ALARP principle.

Offshore operators can choose from a wide variety of alternative production systems including those based on fixed platforms, tension leg platforms (TLPs), compliant towers, floating production systems, and remote subsea systems. These systems involve varying degrees of technical innovation and technological risk. Life cycle costs, including initial costs and operating costs over the life of the project, need to be carefully considered to define systems that will minimize cost and maximize return on investment. The life cycle includes all stages of the project, including design, construction, operation, and decommissioning. To address decision-making issues in the selection of alternative systems, eighteen sponsoring organizations under the leadership of Amoco helped define the Methodologies for Comparison of Alternative Production Systems (MCAPS) project. Conducted during a two-year period (1988-1990), this project developed and illustrated an engineering procedure to assist the process of making rational comparisons among design alternatives for offshore production systems. The example developed to illustrate application of MCAPS was a TLP concept designed for Gulf of Mexico conditions. Four TLP alternatives were analyzed and compared; these involved three production riser alternatives and two tendon system alternatives. This paper addresses the structural and foundation aspects of the two tendon system alternatives. A companion paper (Stahl et al., 1991) addresses the production riser alternative, the alternative system economic evaluations, and the comparison processes. The structure aspects addressed in this paper include both first-phase coarse qualitative and quantitative evaluations, and second-phase detailed quantitative evaluations. The detailed quantitative evaluation is illustrated with structural damage in extreme conditions, including potential overloading of the hull, tendons, and the foundation piles. The paper concludes that MCAPS is not a simple process. It is an intensive interdisciplinary process requiring good teamwork and extensive familiarity with the system being analyzed. The judgmental elements of the process are considerable. The potential benefits of the process include: an improved understanding, qualitatively and quantitatively of risk mechanisms; identification and mitigation of hazards; improved cost-effectiveness of designs; and improved safety. The specific risk numbers generated are less important than the design improvement insights that are developed; these numbers can only serve as a guide to focus attention on those aspects of the project which generate the most risk and to indicate where cost-effective risk reduction measures can be implemented.