A Cost-Effective and Safe Method for Transportation and Installation of Subsea Structures-The Pencil Buoy Method

摘要

The patented Pencil Buoy Method has been developed for transportation and installation of subsea structures. Based on standard equipment onboard ordinary construction vessels in combination with tailor-made special equipment, a cost-effective method is developed. The special equipment consists of a slender pencil shaped buoy, a passive heave compensator and associated rigging. The system allows for installation of various subsea structures such as Templates, Suction anchors and Manifolds, as well as for removal of subsea items. The submerged cargo capacity of the system during installation ranges from about 60 tonnes to 370 tonnes including a recent enhancement including a new passive heave compensator. The capacity during subsea transportation ranges from about 150 tonnes to 370 tonnes. During transportation the system is designed to sustain a typical unrestricted summer storm, while during installation the criteria is equal or better than for typical heavy lift vessels. This paper will present the main principles of the Pencil Buoy Method. The paper will mainly focus on the design aspects related to landing of structures on seabed including installing a structure into another, and will present data from a recent such operation.