First production from the Trell and Trine field development is expected in 2025. Credit: Aker BP.
The Trell and Trine oil fields will be developed as subsea tie-backs to the Alvheim FPSO. Credit: KONGSBERG.
The Trell and Trine oil fields are situated in the Heimdal area of the Norwegian North Sea. Credit: Subsea 7.

The Trell and Trine fields are situated in the Heimdal area of the North Sea, offshore Norway. The two fields are jointly owned by Aker BP (48.42%), Petoro (26.84%), ABP Norway (12.84%), and LOTOS Exploration and Production Norge (11.9%), a subsidiary of Grupa Lotos that is a part of PKN ORLEN.

The operator of the development is Aker BP, a Norwegian oil exploration and development company owned by Aker ASA (37.14%), BP (27.85%) and others (35.01%).

The development and operation plan for the project was submitted to the Royal Norwegian Ministry of Petroleum and Energy (MPE) in August 2022. The life of the project is expected to be 16 years.

The production from the oil fields will have a low unit cost and low carbon dioxide emissions, estimated at 0.3kg per barrel.

Location and reservoir details

The Trell and Trine fields are located in the Alvheim area of the Norwegian shelf, at a water depth between 115m and 125m. The Trell field is situated in production licence 102 F/G, while the Trine field is situated in production licence 036E/F.

The fields lie approximately 24km east of the Alvheim floating, production, storage and offloading (FPSO) vessel, which is operated by Aker BP. The Alvheim area also includes the Boa, Vilje, Volund, Bøyla and Skogul fields, which have all produced oil through the Alvheim FPSO.

The recoverable resources of the fields are estimated to be approximately 25 million barrels of oil equivalent.

Discovery and exploration details

The project includes three discoveries, namely Trell, Trine and Trell Nord. The seabed survey at the site of the three discovery wells was completed in 2013.

The Trell field was discovered 10km east of Heimdal field, in 2014, by the 25/5-9 exploratory well drilled by the Leiv Eiriksson semi-submersible drilling rig. The well discovered a gross oil column of 21m in the Heimdal formation with good reservoir quality.

The exploratory well was drilled by Total E&P Norge, a subsidiary of France-based energy company TotalEnergies, which served as the operator of the Trell prospect before the acquisition of its production licence by Det norske oljeselskap (now Aker BP) in 2018.

The Trine prospect (25/4-2) was proved in 1973, 5km east of Heimdal and at a water depth of 120m. Oil was discovered in the Paleocene age sandstones in the Heimdal formation at a depth of 2,150m.

Trell Nord is an exploration prospect with a high discovery probability.

Trell and Trine field development details

The Trell and Trine oil fields development is proposed as subsea tie-backs to the Alvheim FPSO. They would use the existing facilities and infrastructure in the Alvheim area, including the East Kameleon subsea manifold, production pipelines, gas lift pipes and control cables.

The field development plan proposes one production well each at Trell Nord, Trell and Trine.

The subsea system of the project will include three horizontal subsea trees, two manifolds, control systems, 30km of subsea umbilicals and associated equipment.

Installation of a pipeline and new control cable is planned for 2023.

The wells are proposed to be drilled by a sixth-generation semi-submersible drilling rig, and the drilling is anticipated to start in the first quarter of 2024. Installation of equipment for seabed leak detection is also included in the plans.

Alvheim FPSO details

The Alvheim FPSO has been operating since 2008. It will be upgraded according to the requirements of the new subsea tie-ins from the Trell and Trine field development.

The FPSO is expected to be installed with a production system and new three-phase metering allocation, in addition to having modifications made to the power and control system, hydraulic system, and chemical injection and tank capacity. The gas processing capacity and water treatment facilities are also currently being upgraded.

The flow of wells from the discoveries will be connected to the FPSO through a joint pipeline for processing and export.

The operator hopes to produce one billion barrels through the Alvheim FPSO using new wells and tie-ins, such as the Trell and Trine fields, thereby extending the life of the Alvheim field.

Contractors involved

Sustainable energy solutions provider Aker Solutions was awarded a contract for supplying a subsea production system for the Trell and Trine field development in collaboration with Subsea 7, a Subsea 7 Group subsea engineering and construction company, in August 2022.

Subsea 7 will provide engineering, procurement, construction and installation services for the pipelines, spools, protection covers and tie-ins.