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Investigation report following collision between Big Orange XVIII and Ekofisk 2/4-W

The Petroleum Safety Authority Norway (PSA) has issued ConocoPhillips Skandinavia AS (CoPSAS) a notification of order following the collision between the vessel Big Orange XVIII and the Ekofisk 2/4-W facility on the Ekofisk field on 8 June 2009.

Order vs. notification of order

An order is an individual decision made in pursuance of the regulations.

Before we issue an order, we normally send a "notification of order" to the affected companies.

A notification of order is not a policy instrument, nor a warning of a sanction, but rather a step in our processing according to specific administrative rules.

The notification is merely a first step before an individual decision is made.

An order is a strong, preventive policy instrument that is legally binding on the recipient.

The PSA has concluded its investigation of the incident on the Ekofisk field on 8 June 2009 when the well stimulation vessel Big Orange XVIII collided with the water injection facility 2/4-W on the Ekofisk field.

The investigation uncovered nonconformities in relation to regulatory requirements, and the PSA has now issued a notification of order to the operating company, CoPSAS.

In the early morning hours of 8 June 2009, the vessel Big Orange XVIII was en route to the 2/4-X facility on the Ekofisk field to carry out well stimulation.

The autopilot was not deactivated before the vessel entered the safety zone around the field, and because the autopilot was active during the approach, the planned course changes were not executed in the manner that the duty officer on the bridge expected.

Big Orange XVIII avoided a collision with Ekofisk 2/4-X and Ekofisk 2/4-C, passing under the bridge between these facilities.

The vessel also managed to avoid colliding with the jack-up living quarters facility COSL Rigmar, but did ultimately collide with the unmanned water injection facility Ekofisk 2/4-W.

At the time of the collision, the Big Orange XVIII had a speed of 9.3 knots.

Major accident potential
The incident is categorized as a major accident based on the outcome, as the integrity of a facility was endangered. There was also a potential for a major accident in which several people could have died or suffered serious personal injury.

The size and speed of the vessel resulted in a collision energy up to six times higher than the energy several of the vulnerable facilities are designed to withstand.

Injuries / damage
No personnel suffered physical injury; however, the incident did cause significant material damage, both to the facility and the vessel.

Big Orange XVIII lost equipment such as antennas, masts, etc. from the roof of the bridge, with the accompanying loss of function. The force of the collision caused the bow of the vessel to compress by about two metres.

Ekofisk 2/4-W was in part pushed out of position in that several legs came loose from the main load-bearing structure, which was also pushed out of position.

In addition, the water injection riser for well W-05 was extensively bent. Several wellheads were moved out of position. The bridge connecting Ekofisk 2/4-W and bridge support BS01, were also pushed far out of position when the bridge abutment at Ekofisk 2/4-W was bent down.

Damage has been identified to legs under water, at 2.5 and 15 metres below the sea surface. A local deformation (buckling) has been discovered on the southern leg, near the crossover to the pile. Cracks have been discovered between the jacket legs and the deck on the two northernmost legs (northwest and northeast). The crack on the northwest leg covers about 50 per cent of the circumference, and about two-thirds of the circumference of the northeast leg.

Production shut down
The immediate consequences resulting from the material damage caused by the collision included the need to shut down production from Ekofisk 2/4-A due to lack of overpressure protection.

In addition, the bridge between Ekofisk 2/4-W and bridge support BS01 had to be temporarily secured using heavy lift vessels.

Because the damage to the abutment for this bridge, as well as the damage to both the water injection riser and load-bearing structures on Ekofisk 2/4-W proved to be extensive, a decision was made to remove the bridges connecting Ekofisk 2/4-W with the bridge support (BS01) to Ekofisk 2/4-FTP and to the south flare, including its supporting frame down to 20 metres below the sea surface. This was done to ensure the use of the Mærsk Gallant drilling facility for plugging of a total of six remaining wells on Ekofisk 2/4-W.

2/4-W to be removed
When all the wells are plugged, Ekofisk 2/4-W will be removed. The plan is to carry out the removal operation in 2010.
Production from Ekofisk 2/4-A remains shut down until new overpressure protection is installed and ready for start-up. Parts of the Ekofisk field will not receive sufficient pressure support due to the lack of water injection.

Nonconformities and improvement items
The PSA's investigation of the incident revealed two nonconformities in relation to the regulatory requirements:

  • Deficient monitoring of vessels: ConocoPhillips has not made adequate provisions to ensure compliance with its own requirements for safe entry into the 500-metre zone.
  • Measures not implemented after the Ocean Carrier collision: the suggested measures following the Ocean Carrier collision on the Ekofisk field in June 2005 have not been fully implemented in CoPSAS' own organisation, nor have they been followed up vis-à-vis all vessel contractors.

One improvement item was also observed:

  • Follow-up of management system and internal requirements: There are indications of inadequate compliance with the management system and internal requirements for acceptance of vessels by the operations unit.

Notification of order

Based on our findings during the investigation, we have issued CoPSAS a notification of order, as follows:

Pursuant to Section 58 of the Framework Regulations relating to individual decisions, cf. Section 38 of the Framework Regulations relating to monitoring of safety zones, and Section 22 of the Management Regulations relating to improvement, ConocoPhillips Skandinavia AS is ordered to:

- implement measures to ensure monitoring and control of vessels that enter or are inside the safety zone, and that the required checkpoints are carried out before the vessel is granted permission to enter,
- ensure that proposals for improvement measures from the company's own internal investigation report are incorporated in a binding and dated plan with a person responsible for the implementation.

The deadline for complying with the order is set at 1 December 2009. We must be notified when the order has been complied with.