Application of Risk-Based Design Relative to Health, Environment, and Safety
Authors: Haughie Iain J. 
Published: October 2008

Deepwater Nigeria is an evolving area of development presenting many challenges relative to health, environment, and safety (HES) management. The Nigerian regulations mirror the prescriptive requirements in other producing regions, including requirements for an Environmental Impact Assessment (EIA) and safety studies.

The Agbami field is located offshore Nigeria in the central Niger Delta approximately 70 miles south-southwest from the nearest Nigerian shoreline in water depth ranging from 4250 ft to 5400 ft. During front-end engineering, HES studies and assessments were used to optimize the design of the Agbami facilities beyond the minimum requirements of the regulations. This paper describes the risk-based approach adopted by the Agbami project with respect to HES and the optimization this allowed within the design.

Introduction

Floating production storage and offloading (FPSO) installations are being widely used worldwide for the development of new offshore oil prospects, including West Africa. However, the application of FPSOs in this region involves changes in design from the more familiar concepts. These differences, including physical dimensions, riser configurations, offloading strategy, mooring, and gas handling strategy, result in significant HES challenges.

The development of all new frontiers introduces new challenges for all technical disciplines and this includes HES. Concepts that may work in the North Sea, Gulf of Mexico, or offshore Brazil may not be directly applicable to Deepwater West Africa. Therefore existing regulations, codes, and standards may only provide a foundation for the facilities design. Further analyses, studies, and assessments are required for HES considerations to ensure a design suitable for each specific development. These assessments assist in better decision making, and performing this work early in the design evolution reduces the potential for changes during later stages of the project, thereby reducing overall costs and potential schedule delays.

Risk-Based Design for Decision Making

Conventionally, during the front end and detail engineering design phase, the design is based on codes, standards, and past experience. This is adapted for local regulations, with decisions based on engineering judgment. This approach may not adequately address the technical challenges, including HES, when developing the design of a facility in a new frontier. A risk-based design approach allows optimization and a more informed decision making process to adapt the HES requirements in the design (Fig. 1).

The history of this approach has been in use for many years; however, it was the loss of life in the Piper Alpha incident in 1988 and the subsequent regulatory changes in the UK that witnessed a more widespread acceptance of the risk-based techniques. Many offshore producing regions around the world now adopt regulatory requirements to use risk-based techniques, including Norway, Australia, and Nigeria. As stated within the UK Engineering Council's Guidelines on Risk Issues,1 risk management is not simply the reduction of risk, although this is the intended result. A more realistic objective is to strike an appropriate balance at the conceptual stage between the benefits of reduced risk, the expense of that reduction, and the gains from the enterprise or development.