North Sea platform incident: Serious regulatory breaches come to light after worker injuries and gas leaks

Norwegian state energy giant Equinor has been served with an order notice by the country’s offshore safety authority following an investigation into an incident that resulted in a breach and a gas leak at a platform in the North Sea, located on one of the oldest producing fields in the Norwegian Continental Shelf (NCS).

Last year an investigation was launched into an incident on the Statfjord B Platform that took place on April 22, 2023 when the clamps/blind hub were removed from new production pipes. In addition to investigating the incident, the Norwegian Maritime Industry Authority (Havtil) provided technical support to the police investigation into the incident.

The incident occurred during the splitting of a blind node of a new production pipeline when it was discovered that the system was not completely depressurized. As a result, the pressure in the pipeline threw the 34kg 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 sealing ring weighing 2.15 kg fell into the level below and hit a person without causing any personal injury.

At the time of the incident, seven people were in close proximity during the splitting of the blind hub on the hydrocarbon system and one person was also on the level below. While Havtil emphasized that the subsequent gas leak was short-lived and had a total weight of approximately 2.4 kg, he also stressed that under slightly different circumstances the incident could result in a fatal accident.

The Statfjord B platform stands on the platform operated by Equinor Statfjord field is 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 in 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 was developed with three fully integrated production platforms: Statfjord AStatfjord B and Statfjord C. Statfjord B in the southern part of the field came into production in 1982 and the Norwegian portion of the field lies in blocks 33/9 and 33/12 of production license 037, while the British portion lies in British block 211/25 of licenses 104 and 293.

Sample highlights lessons learned from the incident

In listing the lessons learned from the incident, the Norwegian Maritime Industry Authority’s investigation found that the work permit for the hydrogen system splitting was applied for, processed, approved and activated with an attached isolation plan, which was not relevant to the task at hand to be done.

Havtil points out that this plan was not reviewed in connection with the security clearance of the work, which could have happened because the plan was contained in a file attached to the work permit, which remained unopened throughout the processing of the permit. The file name indicated that the file was relevant to the job.

Given this, the offshore safety watchdog explains that the incident would have been avoided if the isolation plan attached to the work permit had been reviewed before it was put into effect, demonstrating the importance of following established procedures.

In addition, the Norwegian regulator found that when operators checked whether the system was depressurized before splitting, they did not realize that the valve they were trying to open contained a check valve, meaning they had incorrectly concluded that the system is depressurized. The design of the valve used for verification is different from other valves used for chemical injection in the facility. However, this was not known to the responsible staff.

Additionally, Havtil insists that training and documentation are important factors to ensure adequate knowledge of the equipment when a facility has been in operation for a long time and has been modified by the installation of new design equipment.

Non-conformities and improvement points

In addition, the regulator’s investigation identified four non-compliances with the regulations related to the incident, including insufficient security clearances for activities, inadequate communication of information during shift and crew changes, lack of information for relevant users and poor planning of work. Identify important factors that contribute to the risk of an ignition source.

In addition, the investigation team identified a condition categorized as an improvement point related to a lack of capacity to carry out planned activities. Due to the serious breaches of regulations identified during the investigation, Equinor was issued with a disciplinary notice.

Therefore, Havtil has directed Equinor to identify measures and prepare a plan to implement measures to ensure compliance with the requirements for security clearance of activities and the necessary transmission of information on the status of isolation plans during shift and crew changes. The Norwegian giant was also ordered to conduct an internal review to examine whether the measures had the desired effect.

According to the Norwegian Safety Authority, possible comments on the notice should be received no later than April 22, 2024. The deadline for compliance is June 1, 2024 for Sections 1 and 2 of the Ordinance, and June 1, 2025 for Sections 1 and 2 of the Ordinance was set for Section 3. Havtil must be notified if the individual points of the regulation have been complied with.