Grane

Grane Oil Field Profile

Location and Geography

The Grane oil field is located in the central part of the North Sea, approximately 185 kilometers west of the city of Haugesund on the western coast of Norway. It is situated in block 25/11, just east of the Balder field.

Water and Reservoir Depth

The field is in a water depth of about 128 meters (420 feet), with the reservoir located at a total depth of 1,700 meters (5,600 feet).

Geology

The Grane field's reservoir consists mainly of sandstones from the Heimdal Formation of Paleocene age, which is part of the Tertiary period. The reservoir has very good properties, including an average pay thickness of 50 meters (160 feet), an average porosity of 33%, and permeability of 5–10 Darcies. The oil in the field has high viscosity.

Ownership and Operation

The Grane field is operated by Equinor (previously Statoil), with the following ownership stakes:

• Equinor: 38% (or 36.66% as per some sources)
• Petoro: 30% (or 28.94% as per some sources)
• ExxonMobil: 25.60% (or 28.22% as per some sources)
• ConocoPhillips: 6.40% (or 6.17% as per some sources)

Development History

The Grane field was discovered in 1991 by Norsk Hydro. The plan for development and operation (PDO) was approved in 2000. Development of the field began in 1991, and the first oil was produced on September 23, 2003. The facility was designed by Aker Solutions Engineering between 2000 and 2003.

Production

The Grane field started production in September 2003 and reached peak production by March 10, 2006, with a record of 243,000 barrels per day (38.6×10^3 m³/d), exceeding initial expectations. The average production has been around 220,000 barrels per day (35×10^3 m³/d). The field is expected to produce approximately 700 million barrels (or around 950 million barrels as per updated estimates) of oil, with an estimated recovery rate of 55%.

Production Profile

Here is a summary of the annual production from the Grane field:

| Year | Production (million Sm³ oil equivalent) | |-----------|-------------------------------------------| | 2003 | 0.751066 | | 2004 | 7.086147 | | 2005 | 10.307771 | | 2006 | 12.613752 | | 2007 | 11.992443 | | 2008 | 10.037249 | | 2009 | 10.723929 | | 2010 | 9.654461 | | 2011 | 8.097365 | | 2012 | 7.108406 | | 2013 | 5.504911 | | 2014 | 4.085547 | | 2015 | 4.214624 | | 2016 | 4.391 | | 2017 | 5.832353 | | 2018 | 5.62534 | | 2019 | 5.118285 | | 2020 | 3.986892 | | 2021 | 3.063436 | | 2022 | 2.102059 | | 2023 | 2.04668 |

Facility and Infrastructure

The field has been developed with an integrated accommodation, drilling, and processing facility supported by a bottom-fixed steel jacket. The facility includes 40 well slots and living quarters. Key contractors involved in the project include Kvaerner (jacket and piles), Aker Solutions (design and supply of electrostatic coalescer internals), Emtunga (living quarter module and helideck), and Saipem (pipelines and installation).

Transport

The oil from the Grane field is transported via a 212-kilometer pipeline to the Sture terminal in Øygarden, west of Bergen, where it is stored in rock caverns before being shipped to the global market.

Recovery Strategy

The field is produced using gas injection at the top of the structure and horizontal production wells at the bottom of the oil zone. Initially, gas was imported from the Heimdal gas center, but this was terminated in 2010 and reinstated in 2014. The field also employs limited water injection and relies on gas injection and the drilling of new wells, including sidetracks from existing producers, to maintain oil recovery.

Tied-In Fields

The Svalin and Breidablikk fields are tied back to the Grane platform. The Svalin field, located 6 kilometers southwest of Grane, came on stream in March 2014. The Breidablikk field, located approximately 10 kilometers northeast of Grane, is being developed with four subsea frames connected to the Grane platform, extending the lifetime of the Grane platform from 2043 to 2060.

Future Prospects

Production from the Grane field is expected to continue until it reaches its economic limit in 2043. An expansion project, the Grane Gas Export Project, is in the feasibility stage and is expected to start in 2029.

Contractors and Partners

Key contractors and partners involved in the Grane project include:

• Kvaerner: Jacket and piles
• Aker Solutions: Design, manufacture, and supply of electrostatic coalescer internals
• Emtunga: Living quarter module and helideck
• Saipem: Pipelines and installation
• Odfjell Drilling: Drilling services