On Monday June 8th, 2009, well stimulation vessel Big Orange XVIII collided with the structure of the Ekofisk water injection platform 2/4W. The impact caused severe damages to the platform structure, bridge landing and bridge connection on both sides of the installation and to some of the conductors for the 6 water injection wells on 2/4W.
All required information to establish a complete overview and picture of the damage from the collision has yet to be collected. Visual inspection has been performed from a supply boat that was manoeuvred into position close to the installation. Development of procedures, risk analysis and other preparatory work are underway to evaluate access to 2/4W via the existing bridge to obtain a better overview of the damages and enable a thorough structural and well integrity inspection.
Big Orange XVIII was approaching platform 2/4X to perform a planned well stimulation job on well X-16. Weather and wind conditions in the area were well within the acceptable criteria for the vessel involved. The vessel was provided with the required permission from Ekofisk Radar to enter into the area at 04:00 hrs, the vessel entered into the Ekofisk Complex 500m zone the from north at 04:11 hrs. When the vessel was approaching 2/4X and preparing to manoeuvre next to 2/4X for the stimulation job, the vessel experienced a malfunction of the main power machinery at 04:14 hrs. The consequence was severe problems in manoeuvring the vessel which continued forward with an estimated speed of 4.5 knots. The vessel’s Chief Mate was not able to stop or turn the vessel. He therefore decided to use the thrusters to avoid collision with 2/4X. The vessel passed under the bridge between 2/4X and 2/4C at 04:17. At this point the vessel lost all power and manoeuvring capabilities.
The vessel continued in a southern direction moving past jackup rig Port Rigmar on their port side and 2/4Q and 2/4FTP on their starboard side before they hit the structure and jacket on 2/4W with the vessels bow first. It is estimated that the speed of the vessel was around 4.5 knots at the time of the impact. After impact the vessels stern end was turned in under the bridge. The final position of the vessel was next to the 2/4W platform structure stuck under the bridge with the bow pointing east and the stern pointing west. Supply vessel Northern Crusader arrived in the area after 20 minutes, a towing line was used to pull Big Orange XVIII away from the platform structure and the bridges into a secure position on the west side of the installation.
The Boat Coordinator on 2/4H was made aware of the situation after they received a call from Big Orange XVIII after the impact on 2/4W. Members of the local safety preparedness management team on the Ekofisk Complex were informed and they mobilised in the local safety preparedness control centre at 2/4H (LOBS). The onshore safety preparedness management team was informed and mobilised. Emergency shut-down functions were executed to stop the water injection process on 2/4W and the DHSV and XMW valves were closed on all wells. Production was shut-down from 2/4A and all relevant process and pipeline systems were isolated and depressurised. No personnel injuries nor any spill to the external environment has been observed.