All-systems-go for Odfjell Drilling-managed rig’s North Sea assignment

August 12, 2025, by Melisa Cavcic

Equinor, a Norwegian state-owned energy giant, has received the go-ahead from the country’s authorities to undertake plug and abandonment (P&A) activities in the North Sea off the coast of Norway with a semi-submersible rig managed by Odfjell Drilling, an offshore drilling contractor.

Deepsea Bollsta; Source: Odfjell Drilling

The Norwegian Ocean Industry Authority (Havtil) has granted Equinor consent to use the Deepsea Bollsta rig for permanent plugging and abandonment of wells 31/3-Q-21 and 31/2-X-23 at the Troll field in the northern part of the North Sea, where the water depth is 300-330 meters.

The 2020-built Deepsea Bollsta rig, owned by Northern Ocean (NOL), secured work on the Norwegian Continental Shelf (NCS) last year. This sixth-generation semi-submersible rig is of Moss CS60E design and can accommodate 140 people. The semi-sub can carry out operations in both benign and harsh environments at water depths of up to 3,000 meters.

Odfjell Drilling-managed rig going back to Europe for multimillion-dollar work in Norwegian waters

Project & Tenders

Discovered in 1979, with the initial plan for development and operation (PDO) approved in 1986, and updated in 1990, the field came online in 1995. As a phased development was pursued for the Troll field, Phase I focused on recovering gas reserves in Troll Øst and Phase II on the oil reserves in Troll Vest.

While Troll Phase I has been developed with the Troll A fixed wellhead and compression facility with a concrete substructure, Troll Phase II was developed with the Troll B floating concrete accommodation and production facility, and the Troll C semi-submersible accommodation and production steel facility. Troll Phase III came online in 2021.

The operator decided to pursue the second stage of the Troll Phase 3 (TP3 II) project by investing over NOK 12 billion (close to $1.13 billion) to boost the gas infrastructure in the Troll West gas area to accelerate production.

Giant North Sea field sets ‘historic’ gas production record

Exploration & Production

Equinor recently hired Aker Solutions to prepare the topside of the Troll C platform to receive and process production from the Fram Sør subsea tie-in, following the submission of a plan for development and operation (PDO) for the project aimed at bringing more oil and gas to Europe from the Fram and Troll area.