Tie-down loads for drilling rigs and modules on floating structures Conference Paper uri icon

abstract

  • Tie-down systems are used to fasten drilling rigs and modules to decks of deepwater floating drilling and production structures. Several drilling rigs were moved and a few were even toppled during recent hurricanes. This paper describes results of API-sponsored research to (1) analyze the variation and sensitivity of maximum tie-down loads for rigs and modules on different structures, and (2) develop guidance for designing tie-down systems. Tie-down systems are designed to withstand the large loads in severe storms. Tie-down loads are due to the direct wind loads on the drilling rig as well as loads due to the motions of the floating structure. Time series of tie-down loads were simulated for a TLP, Spar, and Semisubmersible in hurricane conditions using a coupled structure and derrick model. Results show that maximum tie-down loads vary significantly with the (1) motion responses of the structure and (2) weight and geometry of the drilling rig or module, indicating that the tie-down systems should be purpose-designed for specific structure and drilling rig. Results from this study are also applicable to tie-downs for large deck modules. A methodology is presented that can provide a simple means to estimate tie-down footing loads. The learnings and results from this study are being incorporated in a revision of API Bulletin 2TD (Tie-Downs). Copyright 2010, Offshore Technology Conference.

author list (cited authors)

  • Ward, E. G., Kim, M. H., & Bae, Y. H.

publication date

  • December 2010