THE JACK-UP PLATFORM FOR OFFSHORE OIL AND GAS EXPLORATION OVERVIEW

Аннотация

A Jack-Up platform can float and be transported, it can be elevated when it arrives on location and its legs will rest on the sea bed. After an appropriate and rigorous site assessment the unit will be ready for operation. Due to the compliant characteristics of the structural system difficult challenges must be overcome by designers and operators. Generally, these challenges are more complex than most offshore structures and the later section in this chapter related to the management of hazards endorses this comment. This article is an overview of the main characteristics of these mobile units. A modern Jack-Up can weigh up to 20,000 tonnes and be capable of operating in 150 m of water in a very harsh ocean environment. Jack-Up platforms are designed and constructed to satisfy the rules of classification societies and classification is a comprehensive verification procedure. In this respect they may be regarded as mobile units together with ships and other marine structures. The main structural features are associated with the hull and the legs and foundation. However, separate sections for Jack-Up structural design and foundation design have been included in the Jack-Up chapter. Transportation is a critical stage when the unit can become unstable, but elevating the structure and the process of jacking can also be problematic. Transportation has been considered as a separate section in this chapter and the examples of accidents as case studies demonstrate the dangers associated with the critical stages of operation. Consideration has been given to the use of high strength steel in this review, but sections related to Fatigue and to Fracture Mechanics have been provided separately in the Jack-Up chapter. The section related to Marine Warranty Survey aspects brings together many of the features of Jack-Up operations and the potential of Jack-Up risk and reliability studies for risk assessment of various operating stages has been explored in the Reliability section within this chapter.