2 Answers

0 votes
answered Aug 21, 2015 by Normandy (21,080 points)

The following should be done at a minimum:

  • Flushing of the subsea networks
  • Decommissioning of the topsides
  • Preparing and disconnecting FPSO/FSO and Buoy (if any)
  • Preparing and disconnecting of the platforms
  • Decommissioning of subsea structures and tie-ins
  • Decommissioning of umbilical, risers, flowlines
  • Well plug and abandonment
  • Subsea survey
  • Removal Contractors to remove the structures
  • Disposal and recyle of the structures
0 votes
answered Aug 22, 2015 by lonstruthers (445 points)
The subsea structures to be removed need to be checked for Naturally Occurring Radioactive Materials (NORM). Material should be classified as potential NORM containing if the measurement is greater than 0.23 ╬╝Sv/hr.

The options for processing NORM can vary from country to country and currently there is no adequate regulation on the issue. The regular waste management companies cannot discard NORM regular equipment to decontaminate them.

A recommended concept is to process NORM sediments and scale using dedicated maceration and grinding machinery to reduce the particle size. The resulting slurry would then be transported to an offshore facility and injected into a designated NORM disposal well. The selected subsurface structure(s) would ensure that NORM waste is injected and contained in an isolated zone, thereby preventing migration.