Skarfjell Oil and Gas Field, North Sea, Norway
Skarfjell oil and gas field is located in the production licences PL 418 and PL 378 in the north-eastern part of the North Sea, in a water depth of approximately 360m. The majority of the field lies in PL 418, with a southern extension into PL 378.
The field is operated by Wintershall Norge who own 35% share of PL 418, in cooperation with licence partners, including Cairn Energy subsidiary Capricorn Norge (20%), Bayerngas Norge (20%), Edison Norge (15%) and DEA Norge (10%).
Overview of the Skarfjell oil and gas field
Skarfjell is the second project operated by Wintershall in the Norwegian North Sea, after the Vega field.
Wintershall and its partners announced the selection of a possible development solution for the field in February 2017, which has been submitted to the Ministry of Petroleum and Energy.
The development solution will be refined through a number of studies before the final investment decision is taken on the project.
The companies involved in the operation intend to submit a plan for development and operation (PDO) to the Ministry of Petroleum and Energy in the second half of 2017.
Production is expected to commence in between 2021 and 2022.
Skarfjell was discovered in March 2012 through the drilling of the 35 / 9-7 wildcat well by the Songa Delta rig to a vertical depth of 2,976m.
Limitation in the rig slot length did not allow for testing of the well. Instead, reservoir and fluid sampling were performed, which provided extensive and adequate data on the field.
Geology and reserves of the Skarfjell field
The discovery well encountered good quality light oil and a significant oil column in Upper Jurassic sandstones.
The field is estimated to contain between 120 and 230 million barrels of oil equivalent, and is expected to produce 60 to 140 million barrels of oil equivalent during the course of its development.
Appraisal of drilling at Skarfjell
Skarfjell's hydrocarbon potential has been appraised with the drilling of two wells by the Transocean Arctic rig, known as 35 / 9-8 and 35 / 9-10S.
Well 35 / 9-8 was drilled in April 2013, approximately 1.8km north of the well site to delineate the discovery. It was drilled to a vertical depth of 3,232m and encountered a 64m-thick oil column in the Heather formation.
A maximum production rate of 300 standard cubic metres (Sm³) of oil and 53,400Sm³ of gas flow per day was achieved from a 13m interval in the reservoir during a formation test on the well.
The second appraisal well was drilled in January 2014, roughly 2km south-east of the discovery. It included a main bore (35 / 9-10S) drilled to a depth of 2,837m, and a sidetrack (35 / 9-10A) drilled to a depth of 2,835m.
The purpose of drilling the second well was to determine the thickness, fluid content, geological properties and extent of the Skarfjell reservoir. The well encountered hydrocarbons in the upper and lower Intra-Heather sandstones and confirmed the southern extension of the field. It also confirmed the presence of a gas cap.
Wintershall ended the appraisal campaign for Skarfjell with the southern well, which confirmed the economic feasibility of the project and also reduced uncertainties in the reservoir quality distribution.
Skarfjell field development
Skarfjell is planned to be developed as a subsea tie-back to the Gjøa platform. The development plan includes two subsea templates connected to the Gjøa platform where oil and gas from the Skarfjell field will be processed and exported.
A new 1,000t topside module will be installed on the platform to handle Skarfjell production. An umbilical and riser will also be installed to provide gas lift and water injection for extracting the hydrocarbons.
Several different development solutions were explored through technical and commercial investigations, and tie-back to the Gjøa platform was ultimately considered the most economical solution.
Gjøa processing facility details
Gjøa is a floating semi-submersible facility equipped with processing and export equipment. It has a production and export capacity of 87,000 barrels of oil and 17 million cubic metres of gas a day.
The platform is the first floating unit to be supplied with power from land, which it receives through a 100km-long submarine cable from the Mongstad refinery.