Full Content is available to subscribers

Subscribe/Learn More  >

Feasibility Stage Assessment of Side-By-Side LNG Offloading Operation

[+] Author Affiliations
Jun Wong, Colin Paton, Cedric Morandini

AMOG Consulting, Inc., Melbourne, VIC, Australia

Timothy Withall, Andrew Kilner

AMOG Consulting, Inc., Houston, TX

Paper No. OMAE2007-29522, pp. 629-638; 10 pages
  • ASME 2007 26th International Conference on Offshore Mechanics and Arctic Engineering
  • Volume 1: Offshore Technology; Special Symposium on Ocean Measurements and Their Influence on Design
  • San Diego, California, USA, June 10–15, 2007
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 0-7918-4267-3 | eISBN: 0-7918-3799-8
  • Copyright © 2007 by ASME


A key driver in assessing the economic viability of floating LNG terminals is the marine offloading operations uptime. Marine offloading operations uptime is the percentage of time on site for which weather conditions are such as to permit offloading operations to be undertaken. Physical model testing or time domain numerical simulation techniques can model these marine offloading operations to a very high level of fidelity. However it is not practical for reasons of time and cost to apply such high fidelity modeling to the long duration data sets necessary to make reliable uptime estimates. Simpler solution methods, which can be used to carry out rapid what if studies as well as provide uptime assessment based on very long data records are therefore required. This paper illustrates that a reliable and fast numerical approach based on frequency domain analysis can be developed and used as a pre-screening tool to identify key marine operations uptime drivers. In this method the process of determining the marine offloading operations uptime involves the following steps: 1. Collect and collate site-specific environmental data. The typical starting point for an uptime analysis will be 5 to 10 years of hindcast environmental data, consisting of records of the average wind, wave and current amplitude over successive 3-hour sea states. 2. Evaluate the expected vessel heading in each successive 3-hour sea state throughout the hindcast record. 3. For each 3-hour sea state, estimate the relative motions between the FPSO and LNGC, at the previously determined vessel heading. From the relative motions estimate the envelope of motions of the loading arms and the maximum tensions in the mooring lines between the FPSO and LNGC. 4. For each 3-hour sea state compare the estimated loading arm motion envelopes and maximum mooring line tensions with the maximum acceptable design values to determine whether offloading would be feasible in this 3-hour sea state. 5. Identify times when there are sufficient consecutive 3-hour sea states to allow the offloading operation to be completed (weather window). Determine the percentage uptime from the ratio of the total of these periods to the total environmental data length. A range of sensitivity analysis can also be performed using this methodology, thereby allowing critical cases to be identified for further examination using the high fidelity model testing or time domain numerical simulation programs.

Copyright © 2007 by ASME



Interactive Graphics


Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In