Safety body starts investigation following Gjøa well incident

Norway’s offshore safety watchdog, the Petroleum Safety Authority (PSA), has started an investigation of a well incident on the Gjøa field when the drill string became stuck fast and blocked the blowout preventer (BOP).

The PSA said on Wednesday that the incident occurred during drilling of production well 35/9-G-4 H on the North Sea field by the Deepsea Yantai drilling rig on 20 September 2020.

According to the safety body, the well had already entered the reservoir section when the string became stuck in the formation while it was being pulled out. During efforts to free it, the string separated into two sections.

These parts of the string blocked the BOP so that the latter was unable to close and prevent a potential well stream leak. No discharges resulting from the incident have been reported.

Neptune Energy reports that a cement plug has been inserted against the reservoir so that barriers have been restored. Work is still underway to remove the two drill string sections from the BOP.

The PSA regards the incident on Gjøa as serious, and an investigation team will look at the planning of the well and implementation of the drilling operation up to the point when the incident occurred.

The main objective of the investigation is to identify the causes of the incident and possible lessons to be learnt and to share this information with the industry.

During its investigation, the PSA will review the course of events, assess the actual and potential consequences of the incident, identify direct and underlying causes, identify nonconformities and improvement points related to the regulations, apply necessary enforcement powers to correct possible regulatory breaches, make public its findings, and contribute to experience transfer to and learning by other players in the petroleum sector.

The Neptune-operated Gjøa field is developed with a semi-submersible production facility and includes four 4-slot templates, as well as one single-slot template on the P1 segment.

Production started in 2010, and in 2019, Gjøa was given the green light for the redevelopment of the P1 segment. It is worth noting that the Vega and Vega Sør fields are also tied-back to Gjøa for processing and further export as well as Wintershall Dea’s Nova.

As for the rig, the Deepsea Yantai – formerly known as the Beacon Atlantic – is of GM4D design and is capable of harsh environment operation and is winterized for operation in Arctic areas.

It is worth noting that CIMC Raffles and Odfjell Drilling signed a four-year management agreement last year, under which Odfjell Drilling would manage and operate the rig.