Garantiana Oil Field, North Sea, Norway
Garantiana oil field is located in Production License (PL) 554 of the Norwegian North Sea in 384m of water. It lies approximately 185km north-west of Bergen and 30km north-east of the Visund field operated by Statoil.
Total E&P Norge is the project's operator and holds 40% interest in PL554, while co-owners Aker BP and Point Resources each hold 30% interest.
The partners are currently undertaking concept studies for the development of the field.
The final investment decision on the field development is expected to be taken in 2018, and first production currently planned for 2020-2021.
Garantiana oil field discovery
Garantiana was discovered by the 34/6-2 S wildcat well, which was drilled by the Borgland Dolphin drilling rig in 2012.
The well was drilled to a depth of 4,335m on the northern extension of the Visund structure.
The primary target was to prove oil in the Lower Jurassic reservoir rocks of the Cook and Statfjord formations, while the secondary objective was to prove oil in the Upper Triassic reservoir rocks of the Lunde formation. The discovery well encountered a 100m hydrocarbon column in the Cook Formation.
A drill stem test was conducted, which saw the well flow at the rate of 670 standard cubic metre (Sm³) of oil and 16,500Sm³ of gas a day. The well was later plugged for side-tracking.
Geology and reserves of Garantiana
Garantiana reservoir is located in the Tampen Spur area on the western part of the Viking Graben. It contains Early Jurassic age sandstones of the Cook Formation.
The field is estimated to contain between 25 and 75 million barrels of recoverable oil. The oil contained in the field is medium-density waxy crude with high asphaltenes content.
The life of field is estimated to be between ten and 15 years.
Appraisal of the North Sea oil field
Garantiana has been appraised by two appraisal wells, 34/6-2 A and 34/6-3 S.
The well 34/6-2 A was a side-track to the discovery well drilled by the Borgland Dolphin drilling rig to delineate the discovery.
It was drilled to a depth of 3,810m in the Early Jurassic Cook Formation. The well encountered oil at 3,701m in the Cook Formation and was then permanently abandoned as an appraisal well.
The second appraisal well, 34/6-3 S, was spud by the Leiv Eiriksson drilling rig and drilled to evaluate reservoir properties, as well as demonstrate the presence of hydrocarbons in the Cook Formation.
The well encountered a 120m oil-bearing column in the Cook Formation. It flowed at the rate of 945Sm³ of oil and 16,731Sm³ of gas during a well test.
A side-track drilled to the 34/6-3 S also encountered small volumes of oil.
Garantiana field development
The developers evaluated a number of development solutions for Garantiana, including a standalone development through a floating, production, storage and offloading (FPSO) facility or tie-back to existing facilities of the Knarr, Visund or Gulfaks fields.
The development is estimated to cost up to Nkr10bn ($1.2bn) and will include three production wells and three water injection wells.
Wood Group has been contracted to carry out concept studies to assess the development of Garantiana as a tie-back to Statoil's Gullfaks B and Visund facilities.