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Shenzi pile dredging in Gulf of Mexico Development and custom design of equipment for dredging of cohesive clay inside piles at 1340 metre depth in Gulf of Mexico.


Project description:

The reserves at Shenzi will be produced using a standalone, tension leg platform (TLP). The facility will have nominal capacity to produce 100,000 barrels of oil and 50 million cubic feet of gas per day. The Shenzi project involved installation of piles at 1340 m sea depth. These piles (Steel pipes) were driven down in seabed to serve as anchors for later installation of the TLP platform. SediCon’s mission was to custom design a dredging tool capable of removing the clay inside the piles.

Location:

The Shenzi project is located in Green Canyon Blocks 609, 610, 653, and 654 in Gulf of Mexico (GOM).

Client:

GTO Subsea, who was awarded the contract by Hereema Marine Contractors. (Netherlands) BHP Billiton is the operator of the Shenzi field. The joint venture participants and their respective ownership interests are BHP Billiton, 44%; BP, 28%; and Hess Corporation, 28%.

Sediment Challenge:

The piles needed to be dredged inside and 10 metre down below original seabed in order to connect to tension legs. The sediments consisted of very fine and cohesive clay. The Pile Dredge needed to be operated from the surface, but guided by an ROV. The Pile dredge fits inside the piles, and dredging had to be performed without any direct inspection or direct control of the dredging inside the piles.

Solution:

SediCon designed a the Pile Dredge based on XXL dredgers which provide significantly increased suction rate and unrestricted diameter up to 16�. A large number of jetting nozzles on the pile dredge provides capacity of breaking up very hard sediments. Its special design ensures blocking is avoided even if the suction head is lowered quickly into the sediments. The sediments can be shifted long distances, at previous projects up to 120 metres.

Date of implementation:

Contract award early 2008, execution in June 2008.

Results:

The Pile Dredging project was successfully completed on time.

Prof. Brochsgt. 2, 7030 Trondheim, Norway, Olav Tryggvasonsgate 24b , 7011 Trondheim, Norway

Tel: +47 73 52 93 00, E-mail: post@sedicon.no www.sedicon.no SediCon Latinoamerica SA P.O. Box 1348-1200 Tel-fax: +(506) 22 39 38 04 COSTA RICA

Shenzi pile dredging inGulf of Mexico  

Development and custom design of equipment fordredging of cohesive clay inside piles at 1340 metredepth in Gulf of Mexico.