Abstract SVIMWS

Since 1996 eight spar-based floating production systems have been installed in the Gulf of Mexico. Another five production spars are slated for installation in the next two years. For spars the Vortex-Induced Motion (VIM) responses of the hull under current flow is an important consideration for the design of the mooring and riser systems. Throughout the past decade a number of operators and engineering firms have made
substantial investments in technology related to spar VIM, whether it be in sophisticated model tests, advanced computer models, or full scale performance data. Much of the information and knowledge derived from these technology development efforts is proprietary and has understandably been kept confidential. The state-of-the-art that has evolved is largely based on fragments of proprietary empirical knowledge held by relatively few organizations.

Industry has not yet had the opportunity to share and review the collective data/knowledge on spar VIM in order to establish a common understanding of the problem and an industry consensus on how to deal with spar VIM in design. Currently there are multiple perceptions of spar VIM, with different organizations having different design procedures along with different views on the associated design uncertainties. It is clear that the industry needs widely accepted and consistent practices for addressing spar VIM in order to ensure the integrity of existing and future spar designs. Such practices must be based on verifiable data if they are to be credible and must allow for any perceived uncertainties.

Motivated by these considerations and under funding provided by the US Minerals Management Service, the OTRC organized and hosted an industry workshop on spar VIM to establish a shared vision for an effective path forward. A Technical Steering Group representing the major industry stakeholders was formed to assist with the planning of the workshop.

The Technical Steering Group met on a monthly basis from March to September, 2003. The primary members of the Technical Steering Group were:

Don Allen – Shell Global Solutions
Luis Bensimon – Kerr-McGee
Mehernosh Irani – Technip Offshore
Rick Mercier – OTRC
Bob Sandström – ExxonMobil
Hugh Thompson – ChevronTexaco
Adam Bangs – SparTEC
Skip Ward – OTRC

Others participated in the Technical Steering Group meetings and provided valuable guidance, including:

Ro Lokken – ExxonMobil
Pierre Beynet, Hugh Banon – BP
Jen-Hwa Chen – ChevronTexaco
Stergios Liapis, Lee Li – Shell
Charles Smith – MMS

The workshop had the following major objectives:

• initiate a path for development of an industry-acceptable design
  practice/methodology on spar VIM,
• identify uncertainties and technical needs in spar VIM and a path forward to fill the
  identified gaps,
• educate industry on the technical challenges involved.

The workshop was held at Camp Allen Retreat & Conference Center, Navasota, Texas from October 22 to 24, 2003. Over 100 professionals from industry, government and academia participated in the workshop.