Statfjord B; Credit: Harald Pettersen/Equinor

North Sea platform incident: Serious regulation breaches come to light following worker injury and gas leak

Norwegian state-owned energy heavyweight Equinor has been served with a notice of order from the country’s offshore safety regulator after a probe into an incident, which resulted in an injury and led to a gas leak at a platform in the North Sea, located on one of the oldest producing fields on the Norwegian Continental Shelf (NCS).

Statfjord B; Credit: Harald Pettersen/Equinor

An investigation was launched last year into an incident on the Statfjord B platform that occurred on April 22, 2023, when the clamps/blind hub were being removed from new production tubing. Aside from looking into the incident, the Norwegian Ocean Industry Authority (Havtil) provided technical support for the police inquiry into what happened.

The incident took place during the splitting of a blind hub on a new production pipeline when the system turned out not to be fully depressurized. As a result, the pressure in the pipeline threw the 34-kg hub about 1.5 meters into the air, which then hit a person on the way down, breaking their nose and jaw. In addition, a 2.15-kg sealing ring fell to the level below and hit a person there, without causing a personal injury.

At the time of the incident, seven people were in the immediate vicinity during the splitting of the blind hub on the hydrocarbon system and one person was also present on the level below. While emphasizing that the subsequent gas leak was of brief duration and totaled about 2.4 kg, Havtil also highlighted that the incident had the potential to become a fatal accident under slightly different circumstances.

The Statfjord B platform stands on the Equinor-operated Statfjord field located in the Tampen area in the northern part of the North Sea on the border between the Norwegian and British sectors. Equinor describes Statfjord as one of the oldest producing fields on the NCS and the largest oil discovery in the North Sea. The Norwegian share of the field is 85.47% and the water depth at the site is 150 meters.

Discovered in 1974, the Statfjord field has been developed with three fully integrated production platforms: Statfjord A, Statfjord B, and Statfjord C. Statfjord B in the southern part of the field came into production in 1982 and the Norwegian share of the field lies in blocks 33/9 and 33/12 in production license 037, while the British part is in the UK block 211/25 in licenses 104 and 293.

Probe spotlights lessons learned from the incident

While listing the identified lessons from the incident, the Norwegian Ocean Industry Authority’s investigation found that the work permit for splitting the hydrogen system was applied for, processed, approved, and activated with an attached isolation plan, which was not relevant to the job that was to be done.

Havtil points out that this plan was not looked at in connection with the safety clearance of the work, which could happen because the plan was contained in a file attached to the work permit that remained unopened throughout the processing of the permit. It had a file name that could suggest it was relevant to the job.

With this at the forefront, the offshore safety watchdog explains that the incident would have been avoided had the isolation plan attached to the work permit been checked before the latter was activated, demonstrating the importance of complying with established procedures.

In addition, the Norwegian regulator found that the operators did not notice the valve they chose to open incorporated a check valve when verifying that the system was depressurized before splitting, which meant they erroneously concluded that the system was depressurized. The design of the valve used for verification differs from other valves used for chemical injection in the facility, but this was unknown to the relevant personnel.

Furthermore, Havtil is adamant that training and documentation are important factors for ensuring adequate knowledge of the equipment where a facility has been in operation for a long time and modified by installing equipment with a new design.

Nonconformities and improvement points

Moreover, the regulator’s investigation has identified four nonconformities from the regulations in connection with the incident, including inadequate safety-clearance of activities, inadequate information transfer at shift and crew changes, lack of information for the relevant users, and planning of the work failed to identify important contributors to ignition source risk.

Additionally, the investigation team pinpointed one condition categorized as an improvement point related to a lack of capacity for executing planned activities. Due to the serious breaches of the regulations found during the investigation, Equinor got a notice of an order.

Therefore, Havtil has ordered Equinor to identify measures and establish a plan for implementing measures to ensure compliance with the requirements for safety-clearance of activities and necessary transfer of information on the status of isolation plans at shift and crew changes. The Norwegian giant has also been ordered to conduct an internal verification to investigate whether the measures have had the desired effect.

According to the Norwegian safety regulator, possible comments on the notice were to be received no later than April 22, 2024. The deadline for complying is June 1, 2024, for sections 1 and 2 of the order, while June 1, 2025, has been set for section 3. Havtil needs to be notified when the individual points in the order have been complied with.