This paper is a follow-up to OTC 4481:- Kulluk - An Arctic Exploratory Drilling Unit, presented at the 1983 OTC. A comparison between the original design basis of the rig and the first year's operational results is presented. The items compared are the towing performance, mooring system performance, the hull structure, and the drilling system. The towing and mooring system comparisons cover both open water and ice conditions. Ice management by icebreakers and logistics problems are reviewed.
The Conical Drilling Unit Kulluk was designed by Gulf Canada Resources Inc. and built in the Tamano Works of Mitsui Engineering and Shipbuilding Co. Ltd. The Kulluk was delivered on schedule on April 2, 1983. After loading equipment and supplies, the Kulluk was towed out of Tamano on April 15, 1983. The schedule that was presented in the original paper was attained within one day of each milestone. This was achieved despite a year when the ice condition was abnormally severe.
This paper will compare the first year's operational results with the rig's design criteria.
The areas covered will be:
environmental conditions
hull shape effects, both in a moored and in a towed condition; open water and ice covered water conditions
hull structural concerns
drilling system.
The paper will also describe some of the planned improvements for the Kulluk's operations.
The Kulluk was designed to the following conditions:
Water depth - 24-55m
Air temperature range -50°C to +20°C
Open Water - one year return storm
2.8m significant wave height 8 second peak period
45 km/hr. sustained wind
0.5m/sec. current velocity
Ice Conditions
1.2m ice thickness
55km/hr. sustained wind
0.3m/sec. current velocity
Open Water - 100 year return storm
7.3m significant wave height 12.5 second peak period
110 km./hr. sustained wind
0.7 m/sec. extreme current velocity
Ice Conditions
The mooring system must be capable of releasing from the anchors prior to the loads reaching 50% of rope breaking strength.
Many of the pertinent design features of the Kulluk mooring system apply to both open water and ice conditions.
The Kulluk mooring system has been designed for use in the Canadian Beaufort Sea in water depths between 24m and 55m. It consists of a 12-point mooring system with 90mm wire mooring lines, mooring winches and high holding power anchors. The 12 anchors are radically dep1oyed at equal angles. The lower fairleads are well below the ice surface on the bottom of the hull to avoid ice contact. This mooring system enables the Kulluk to respond to ice forces from any direction.
