Na Kika Hull Design Interface Management Challenges and Successes
Authors: Kenney J.J. , Harris K.H. , Hodges S.B. , Mercier R.S. , Sarwono M.B.A. 
Published: October 2008

The Na Kika Development is located in the U.S. Gulf of Mexico. The project is a subsea development of five independent hydrocarbon fields tied back to a centrally located, permanently moored floating development and production host facility. The Na Kika host consists of a semisubmersible hull moored in 1936 meters of water supporting four topsides modules. The water depth, the projects flow assurance strategy and an organizational goal to reduce design cycle time and fabrication costs posed numerous challenges to the Hull Global, Structural and Systems Design Teams.

This paper presents the hull design challenges and solutions thereof and highlights the management interfaces that were established early and set the stage for project success.

Introduction:

The Na Kika hull represents Shell's first deepwater semisubmersible design. The hull design, inclusive of global sizing, was completed in thirteen months. The hull detailed structural design was completed in nine months from hull size freezing to the issuance of lump sum quality Approved For Construction (AFC) drawings. This was several months faster than Shellâ??s previous best effort for a similar sized TLP hull and was accomplished without sacrificing design quality. This design cycle reduction was accomplished despite many design firsts, including record water depth for a permanently moored semi-submersible, a new flow assurance strategy utilizing integral wet and dry oil displacement tanks located in the hull pontoons and numerous regulatory uncertainties.

The design challenges, coupled with the cycle time reduction goal, were achieved by establishing early direct interfaces between design teams. The Hull Global, Structural, and Systems Design Teams, inclusive of Regulatory Affairs, interfaced very closely amongst themselves, as well as with the Topsides, Mooring, Subsea, and Construction Teams.

The close coordination and interfacing between design teams enhanced each individual team's ability to eliminate false starts, to understand the quality level of information coming from the other teams and to react quickly to change. Na Kika specific examples of interface management are included herein to further the readers understanding of the processes used.

Design Organization:

To meet the Na Kika host system design challenges, the Na ika Structural Leadership Team (NSLT) was established in Houston and consisted of the following Design Teams: Hull Global and Structural, Mooring, Topsides Structural and Riser. The Subsea Design Team and the Construction Team were located in Houston and were integrated into the NSLT on a need be basis. The Hull Systems Design Team and the Regulatory Affairs group were organized under the Topsides Facilities Design Team located in New Orleans; dual locations created additional interfacing challenges.

The design team personnel were primarily Shell and Shell contract employees and all designs and drafting were performed in-house with the exception of the hull structure. An integrated Shell and ABB Lummus Global design team, under the terms of an established Partnership Agreement, performed the hull structural design and drafting. Both companies provided supervisors and engineering personnel to the Hull Structural Design Team making it a truly integrated team. Shell personnel were involved in all design aspects and assumed the principle responsibility of interface management between the Hull Structural Design Team and the NSLT.