Workers scrambled to escape a topsides swinging from a crane and wire cables flailing about and snapping when a lift went badly wrong off the WA coast in early July.

The incident occurred during the recent decommissioning of Santos’ Sinbad platform near Varanus Island.

According to an environmental approval document, Santos planned to remove the topsides from the steel column, or caisson, that supports it in two steps.

First, the circumference of the caisson would be partially cut through with a flame cutter. Then a construction vessel’s crane is connected to the topsides and takes its weight while the caisson cut is completed to allow the topsides to be lifted.

A terrifying video taken on July 5 from the Allseas Fortitude that was lifting the platform shows how close two or three rope access technicians perched on the side of the caisson came to serious injury or death.

The topsides can be seen to be rocking back and forth above the workers, then with a loud bang, the caisson separates at the height of the worker’s heads. Numerous dropped objects fall into the sea but appear to miss the workers.

Next, the topsides tilted away from the workers and swung out from the vessel dragging a metal cable past the workers.

The topsides then swung wildly back over the workers and towards the vessel, but by this time, the crane has lifted it higher, so it was above the workers.

Allseas Fortitude in the Tyra field, Denmark
Allseas Fortitude in the Tyra field, Denmark. Source: Allseas

The crew on the boat also could have been in the firing line. As the topsides then swung away from the vessel, a cable broke, and a heavy piece of metal with cable attached was flung towards the boat. This happened again on the next swing of the topsides.

Experienced offshore construction people told Boiling Cold that the lift might have been safer if a jack-up rig that sits on the seabed was used instead of a vessel that moves with the ocean.

Some believe the tension in the cables above the platform during the final caisson cut was too high.

Santos plans to decommission up to 17 structures in the area over the next five years.

The Sinbad and Campbell platforms were installed in 1993 by US-based Apache and ceased production in 2006. For the past 15 years, they have been inactive.

In 2018 Apache’s assets around Varanus Island were sold to Quadrant Energy, which Santos bought in 2018.

Santo awarded the contract to decommission the Sinbad and Campbell platforms to Fugro. The Dutch company, in turn, contracted Allseas to supply the Fortitude construction vessel and AusGroup subsidiary MAS for rope access technicians.

As the Sinbad platform is near Varanus Island, it is in State Waters and regulated by the Department of Mines, Industry Regulation and Safety.

A spokesperson for the Department of Mines, Industry Regulation and Safety said the incident was still under investigation by Santos and the Department.

“Until the investigation is completed, a Prohibition Notice has been issued to Santos directing Santos not to conduct any other lifts of this kind,” the DMIRS spokesperson said.

map of the location of the Sinbad and Campbell oil platforms off the coast of Western Australia
Source: Santos environmental plan

A Santos spokesperson said all activities ceased and the regulator notified as soon as the incident occurred. Sants has provided the results of its investigation to DMIRS.  

"Following the incident and investigation, work recommenced on the remaining Sinbad offshore structure and the removal of the facilities has now been completed," the Santos spokesperson said.

"Santos is working with the regulator to ensure corrective measures are implemented for any future activities to ensure such an incident does not happen again."

The Campbell platform was not been decommissioned and, according to vessel traffic monitoring site MarineTraffic, the Allseas Fortitude is sailing to Singapore.  

Sinbad offshore gas platform design drawing
Sinbad platform design. Source: Apache environmental submission 

Updates:

31 July 2021: Santos comments added, contracting companies added, workers identified as rope access technicians, Campbell platform not decommissioned.

2 August 2021: additional video added.

Correction:

13 August 2021: AusGroup subsidiary is MAS, not MAC.


Main image: Screenshot of video.