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A surface BOP system with a seabed isolation device (SID) was successfully used to extend the water depth capability of the D.P. semi-submersible rig Stena Tay for exploration drilling activities in ultra-deep water to 2,887 m offshore Brazil and to 2,447 m offshore Egypt in 2003. This provided the necessary experience to take the next step towards reducing the cost of deepwater developments utilizing a surface BOP system deployed from an earlier generation, lower specification, deepwater rig. This paper presents the configuration and specifications developed for the surface BOP drilling and subsea completion system to be deployed offshore Brazil in the first phase of the Parque das Conchas development (block BC-10) that encompasses several reservoirs in up to 2,100 m of water. The rig selected for the project had to meet certain minimum requirements to safely deploy the planned surface BOP system, and these requirements led to the selection of the Arctic I, a moored rig capable of operating in 945 m of water using a conventional 18-3/4" subsea BOP stack and marine riser system. The new elements incorporated in the surface BOP system include: Site specific pre-laid polyester taut-leg mooring systemSlim-bore wellhead system (to land production casing hanger)Purpose built 16" OD high pressure riser system (to replace casing riser)Added pressure test hose line, strapped to riser (to pressure test tubing hanger & packer)Replaced lower shear ram in SID with fixed 7-5/8" pipe ram (to seal on ported slick joint)Added power and hydraulic lines in SID umbilical (to reduced ROV support needed)Vertical subsea tree, Tubing Head Spool and slim bore tubing hanger with hydraulic running tool Development drilling operations with this surface BOP system are now expected to commence in the first quarter of 2008. |
