Aasta Hansteen Subsea Production System for Deep Water and Harsh Environment

The Aasta Hansteen Subsea Production System is a part of a new major deep water gas development located in the Norwegian Sea, north of the Arctic Circle and 300 km from shore, west of the city of Bodø in Norway. With a water depth of 1300m, this development is a new water depth record in Norwegian waters and it is characterized by its remote location and harsh environment. The objective of this paper is to present the concept selections, technology development, design and fabrication for the subsea production system including umbilical and workover system. The paper demonstrates the importance of solid preparation in early phase planning, continuous implementation of lessons learned and an extensive test program in order to verify the new technical solutions for the Aasta Hansteen subsea deepwater development. This included development of a new mono-pile "toast rack" template designed for guideline less installation of manifolds and X-mas tree systems. This paper also presents a new deep water Workover system, involving an extensive qualification program and several new technical features such as a new safety joint, heave compensator and automated make-up of riser joints and more, in order to improve operational efficiency and increase safety under given challenging conditions. The paper also addresses a full scale wellhead testing in order to verify the design for fatigue performance. Several novel technologies were qualified and implemented as part of the Aasta Hansteen Subsea Production System to adapt to deep water operations, to enhance HSE performance and improve efficiency of the system. The experience is that the new technologies and new system solutions have improved HSE performance, operational performance and installation friendliness.