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Shell INDE Decommissioning Project

Shell INDE Decommissioning

Project Overview

The Indefatigable gas field lies 75km off the East Anglican coast in the Southern North Sea in water depths of approximately 31m, and was discovered in 1966. The field was developed in phases from 1970 to 1988. Two blocks are owned by Shell/Esso and two are owned by Perenco.

The Shell/Esso blocks comprise 26 Wells, 6 Platforms (Juliet-D, Juliet-P, Kilo, Lima, Mike and November) three inter-field pipelines, two export pipelines and two inter-field umbilicals.

Having reached the end of its useful productive life, production from the Indefatigable Field (Shell Side) ceased in 2005 and the production facilities are being decommissioned

Decommissioning will be performed in a phased manner and will involve the complete removal of all six Inde platforms and in-situ decommissioning of the three inter-field pipelines and the two export pipelines.  The two inter-field umbilicals will be removed to shore for re-use, recycling or disposal as appropriate.

The offshore decommissioning activities commenced in October 2008 and are scheduled to be completed by the end of the first quarter 2012, effectively leaving a 'clean sea'.

Scope of Services

Consub was contracted to provide support in the following decommissioning activities:

  • Hydrocarbon cleaning of the two export pipelines and one inter-field pipeline.
  • Injection of contaminated pipeline fluids into a disused Inde Juliet well.
  • Use of the FPSO BW Carmen to remove contaminated liquids to shore.
  • Cut and removal of all riser base spools.
  • Burial of pipeline ends and any remaining spans and exposures.
  • Cut and removal of subsea umbilicals.
  • Debris clearance at platform locations and along pipeline corridor.
  • Final acoustic and biogenic reef survey at platform locations.
  • Handover of decommissioned pipelines to the Shell Asset.

Consub’s support consists of the following services:

  • Management of the client’s pipeline contractor, to ensure timely preparation for offshore operations, and provide general technical input to the work.
  • Monitor and report on accruals and actuals for the subsea budget.
  • Participate in the relevant HAZIDS
  • Technical input to assist in the engineering and construction aspects of riser cutting, span remediation, etc.
  • Assist the client in procurement of temporary equipment for the work.
  • Preparation and submission of applications for modifications to the Pipeline Works Authorisations (PWA) and the approved de-commissioning plan to DECC.
  • Liaison with DECC and other third parties organisations such as the fishermen’s federation’s.
  • Legal agreement with 3rd party (Perenco) for the disposal of Inde assets inside the Per 23a 500m zone.
  • Crossing agreements for anchoring of the heavy lift vessel over the Perenco Davy Pipelines and other partnered Shell Asset pipelines (Caravel)
  • Investigate innovative techniques to remove the bulk debris from 1 km2 around the platforms and 200m corridor along pipeline routes, this includes possible use of fishing vessel and gorilla type nets for debris recovery.
  • Supervise client’s pipeline contractor during the offshore pipeline cleaning operations.