The Relocation of the SSDC/MAT in 1987

Abstract

The Canmar SSDC/MAT drilling unit was relocated in the U.S. Beaufort Sea in the fall of 1987. The relocation plan consisted of the initial breakout phase, the lift before the tow, the tow to the new drilling location, and the setdown on the new location. This paper discusses some of the experiences gained during the relocation. The main concerns for relocation of a bottom-founded drilling unit are the soil suction and adhesion effects, the time required for lifting free of the seabed, the stability during breakout, the control that can be exercised over the unit when it breaks free of the seabed, and the positioning and ballasting accuracy that can be achieved during setdown. This relocation has shown that lift-off in adverse or soft cohesive soil conditions is not limited by the suction breaking capability of the unit. The relocation also showed that high horizontal position accuracies were achieved during setdown. Comparisons are made between the target procedures developed in the planning stage and the actual procedures monitored during the relocation. A brief description is given of the equipment installed on board as used for the control and monitoring of the operation. The design operating requirements of the unit are highlighted.