0

Full Content is available to subscribers

Subscribe/Learn More  >

Lift Installation of a Subsea Oil Storage Tank: A 60,000mT Pendulum

[+] Author Affiliations
Jorick Velema, Job Bokhorst

Heerema Marine Contractors, Leiden, Netherlands

Paper No. OMAE2015-42191, pp. V001T01A054; 9 pages
doi:10.1115/OMAE2015-42191
From:
  • ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering
  • Volume 1: Offshore Technology; Offshore Geotechnics
  • St. John’s, Newfoundland, Canada, May 31–June 5, 2015
  • Conference Sponsors: Ocean, Offshore and Arctic Engineering Division
  • ISBN: 978-0-7918-5647-5
  • Copyright © 2015 by ASME

abstract

In August 2014 Heerema Marine Contractors (HMC) have successfully installed the Solan Subsea Oil Storage Tank (SOST), using its Semi-Submersible Crane Vessel (SSCV) Thialf. The SOST installation is regarded as unique due to its dimensions, complex hydrodynamics and the utilization of nearly the full crane capacity.

The Solan SOST is a Subsea Oil Storage Tank with a future storage capacity of 48,000 m3 of oil. The SOST has a dimension of 45m × 45m × 25m, a dry weight of 9,500mT and a total submerged mass of 60,000mT including ballast water. It was installed offshore west of the Shetland Islands at a depth of 135m. Prior to installation the SOST was wet-towed to the field. At location the SOST was installed by a dual crane lift sequence, lowering the SOST from 2m freeboard to the seabed. The lowering sequence is characterized by the usage of a compressible air pocket to reduce hookloads during the most critical stage of the installation, the lowering of the SOST through the splash zone.

Prior to the installation ballast and dynamic lift models were generated to understand both the hydrostatics and hydrodynamics of the SOST - SSCV Thialf system throughout the installation. Numerical simulations of the flooding operation were performed to predict all relevant parameters for various scenarios. The lift dynamics were analysed with frequency domain models. Most resonance modes between SSCV Thialf and SOST were found not to be excited due to the differences in natural periods of the hydrodynamic systems and the occurring wave periods.

During installation vital parameters such as ballast volume, compartment fill rates, differential pressure and hookloads were continuously monitored with dedicated measurement systems. The values were compared with the results from the engineering models. As some of the parameters were directly related to each other, the values could be back-calculated and cross-checked, thereby increasing the reliability of the measurements.

Both the understanding of the principle hydrostatics and hydrodynamics of the system as well as the close monitoring of all vital parameters have resulted in a safe and controlled installation of the Solan SOST by the SSCV Thialf; the installation of a 60,000mT dual crane pendulum. This paper describes the hydromechanic engineering work performed by HMC and the SOST offshore installation.

Copyright © 2015 by ASME

Figures

Tables

Interactive Graphics

Video

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

NOTE:
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