Seabed preparation at Heimdal

Scope of Work

Heimdal gas field is located in the central part of the North Sea.

As preparation towards an upcoming by-pass operation, Scanmudring was contracted to make 4 pits under existing pipelines so that PRS could flush concrete (CRU) and Force could scan material quality on the pipes. The scope included dredging of the specific tie-in locations as well as levelling a rock berm at pipe crossing location and potentially boulder removal along the locations of the spools.



Main Spread



Extended plastic suction nozzle(1,5m), exhaust system, emergency umbilical cutter

Water Depth



24 days



Image Caption: Simulating pre- and post-dredging at one location

Planning Phase

  • The dredging was to be carried out near existing subsea assets right outside the 100 meters safety zone of the respective platforms, so planning and safety aspects had to be made accordingly
  • A lot of equipment were to be mobilised for this campaign, and to ensure an efficient mobilisation and offshore campaign, both Scanmudring and the client had to be well prepared to maximize project execution. Scanmudring used our simulation tool to give input on the production rate based on the information received 
  • There were some deposit areas defined by the client which required the use of exhaust system. As repositioning of hoses and cribs could be very time-consuming, Scanmudring recommended the opposite approach; defining an area where no dumping was allowed and limit the use of exhaust system to a minimum.
Specific Tooling

20Te Scanmachine spread including

  • 1,5m extended plastic suction nozzle
  • Exhaust system for high precision on placement of material
  • Emergency umbilical cutter
  • 14” ejector

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