HOUSTON -- FloaTEC has completed Phase-2 testing of its latest ultra-deepwater dry tree units, the extendable draft Semi (E-Semi) and the truss semi (T-Semi). The model test programs were conducted at the Bulgarian Ship Hydrodynamic Center in Varna, Bulgaria and the Offshore Technology Research Center (OTRC) at Texas A&M University in College Station, Texas, respectively.
Both units are low motion semis that are now qualified to support dry tree risers in ultra-deepwater up to 10,000 ft (3,048 m). The units feature quayside integration capability, eliminating the need for a heavy lift construction vessel offshore to install the topsides, the company says.
The objectives of the in-place model tests were:
- To confirm applicability of the units' design for Gulf of Mexico (GoM) post-Katrina metocean conditions.
- To confirm that the air gap is sufficient.
- To verify numerical predictions of in-place global responses, including platform offsets, deck accelerations, and mooring line/riser tension responses
- To measure the forces at the truss-hull connections, and riser top/bottom tension
Although the tests were based on a unit in 4,300 ft (1,310 m) water depth, the design can be scaled to accommodate payloads in water depths up to 10,000 ft (3,048 m), the company says.
Both designs utilize a modified version of FloaTEC's proprietary deep draft semi hull design and rely on hydrodynamic interaction between the heave plate and the hull to reduce motions. The draft provides construction flexibility and the motions are limited to enable the use of commercially available tensioners, currently limited to under 30-ft (9.1-m) stroke.
Since the deepest dry tree system currently installed is in only 5,610 ft (1,710 m) of water, extending the water depth capability of dry tree systems to 10,000 ft (3,048 m) will enable cost effective development of many new discoveries, the company says.
FloaTEC expects to make both designs commercially available in 2009.