Practical Experience Gained Operating a Compact Ultradeepwater Drill Ship

Abstract This paper describes the practical experiences gained during the first year of operation of a new Panamax-size ultra deepwater drill ship. The vessel started operations in the Gulf of Mexico in July 2012. The practical experience is offset against the vessel's design expectations: improved safety, an increased drilling efficiency and reduced operational costs. The drill ship is of an integrated design covering vessel, drill tower and equipment handling. The drill ship offers an equal payload compared to other ultra deepwater drill ships but at half the displacement. This paper details the effects of the highly automated onboard material and equipment handling on the vessel's drilling efficiency and on the operational cost. The material and equipment handling is designed around the box girder drill tower that has no V-door limitation and features a drilling side and a construction side, thus minimising flat time. Stands built on one side of the tower can be stored in two set back drums, one on each side of the tower, and taken out when needed. Four pipe handlers are available for handling purposes. This paper covers the field experience with all features of the drill tower that are designed to save time and/or increase efficiency and/or enhance onboard safety. These include the drill tower's dual drawworks eliminating slip-cut procedures, the passive and active heave compensation on the drawworks, and the splittable blocks. The latter allow increasing the block speed for lighter loads. Introduction The tendency in rig building has been an evolutionary trajectory to larger and larger units - currently up to approximately 100,000mt displacement - to enable operations at remote locations, in extreme water depths and under difficult drilling conditions. The building costs and thus the day rates of these units are high. Given their size, the fuel consumption and associated costs and emissions can be significant compared to smaller units. Furthermore, their large sizes limit their field of operation as they are not able to pass certain canals or bridges. In 2007 Huisman started to design a revolutionary unit. The design objectives were to create a compact drill ship capable of drilling complex wells in ultradeepwater. Huisman utilized its integrated design approach: a team of engineers with various disciplines such as Mechanical Engineering, Naval Architecture, Electrical Engineering etc. worked simultaneously together with clients, Noble Drilling and Royal Dutch Shell, who delivered valuable operational input. After approximately 10 months of engineering and various discussion sessions with the clients, Huisman presented the HuisDrill 12000 design.