Dry tree semi solution for deepwater production
Judy Maksoud
International Editor
LISBON, Portugal -- To date, the two traditional hull forms that support dry tree top tensioned risers for deepwater applications have been the spar and the tension leg platform. John Murray, director of technology at FloaTEC, told participants at the International Offshore and Polar Engineering Conference on July 4 that a new dry tree semisubmersible design is a viable alternative in ultra deepwater.
Dry trees allow workover, drilling, and completion from the drillfloor, Murray said, so there is no need for a mobile offshore drilling unit to be used for drilling and workover.
Murray presented a new deepwater dry tree floater design that he described as, "having the motions of a spar and the functionality of a semisubmersible." A number of design variations have surfaced that combine semisubmersibles with heave plates, he said, explaining that the strategy is to design the semisubmersible's draft to be shallow enough for quayside integration and to position the heave plate after the hull is moved to deepwater.
"All of the riser technology developed for the spar can be transferred directly to the dry tree semi," Murray said.
Murray showed the results of analysis indicating that within a practical range of relative sizes of the pontoon, columns, and heave plate can be dimensioned to influence the heave RAO, natural period, and cancellation period to optimize the design for a particular operating environment.
"Semisubmersible hull forms with heave plates can be designed for dry tree applications," Murray concluded. "By the end of this year, FloaTEC will be ready to offer a dry tree semi to the market."
July 4, 2007
Page 1 of 1
Add RSS Feed