The Goliat oil and gas field, located in the production licence (PL) 229 in the Barents Sea, north of Russia and Norway, is the first oil reservoir to start production in the area. The PL was awarded in 1997, which increased the interest of oil and gas industry in the region.
The PL229 is owned by Var Energi AS (65%) and Equinor Energi AS (35%) and operated by Var Energi AS.
The discovery well was drilled in 2000. The Norwegian Parliament approved the plan for development and operation (PDO) of the field in June 2009, while first oil from the field flowed in March 2016.
Current production capacity of the field is approximately 110,000 barrels of oil per day, including gas.
The field is expected to be in production for up to 15 years.
Goliat main reservoirs of oil and gas
Goliat has two separate main reservoirs, the Kobbe and Realgrunnen, and contains oil with an overlying gas cap.
The Realgrunnen reservoir is situated 1,000m below sea level and the Kobbe reservoir is 1,800m below sea level. There are also minor oil discoveries in the Snadd and Klappmyss formations.
The reservoirs are characterised by low pressures, 123bar from Realgrunnen and 192bar for Kobbe. This presents potential challenges for production flow.
Approximately 1.3 billion cubic metres of gas is produced and re-injected into the field every year. The gas from the field is re-injected into the Kobbe reservoir or transported to Melkoya.
Goliat field development details
Goliat field includes a cylindrical floating, production, storage and offloading (FPSO) facility, called Sevan 1000 FPSO, and eight subsea templates with up to 32 wells.
The subsea templates are tied-back to the FPSO. The production wells were drilled using Scarabeo 8 semi-submersible rig. The field also includes 24 subsea trees, subsea control systems, steel tube umbilicals and workover systems.
The Goliat platform is equipped with a gas turbine with heat recovery and recycling to provide the necessary process heat. The electric cable from shore is dimensioned to allow for an increase in energy supply.
A 16t helideck was installed at a height of 489ft on the platform, certified by Helideck Certification Agency.
Sevan 1000 is a cylindrical, geostationary FPSO with a hull diameter of 90m, 25 riser slots and 14 mooring lines. Weighing 22,500t, the FPSO topsides include the process plant and utilities.
The FPSO has a process deck area of 9,000m2 and main deck area of 8000m2. It can accommodate 120 people on board, while its crude storage capacity is 950,000bbl. The crude oil can be exported to a shuttle tanker at a speed of 8,000m3 per hour.
The vessel has several features to reduce its impact on environment. It is based on advanced technology to respond immediately in case of oil spill over the project. The 87m-long Esvagt Aurora vessel is used to transport oil from FPSO to tanker vessels.
FPSO power supply system
The FPSO receives power from a new shoreside power supply system at Hyggevatn in Hammerfest. The power supply system comprises 90kV-132kV subsea power cable rated to provide a minimum of 60MW, along with overhead transmission lines and an advanced reactive-power compensation system.
Weighing 6,000t, the power cable is approximately 1,065km long and runs from substation to the FPSO.
Powering the FPSO from land reduces carbon dioxide emissions by half, compared with on-board gas turbines and generators.
Sevan Marine provided project and engineering management, as well as preliminary services for developing the FPSO.
Technip Norge received a flowlines, riser systems installation and connection contract in October 2009. In addition, subsea templates and manifolds, riser bases and umbilicals were installed. The contract is valued at NOK1.7bn ($304m).
The EPC contract for a subsea production system worth NOK2.3bn ($389m) was awarded to Aker Solutions in September 2009.
In January 2010, the company signed a letter of intent with Esvagt for ensuring the safe delivery and standby of a vessel to be used for operation during the project.
Eni awarded the EPC contract for the Goliat FPSO to Hyundai Heavy Industries in February 2010. The $1.16bn contract included onshore commissioning and transportation of the FPSO to the field.
Hyundai subcontracted McDermott for engineering work, while CB&I provided engineering services for the topside, utility and other modules of the Goliat FPSO under a $50m subcontract.
The FPSO was built at the Hyundai Shipyard, in Ulsan, South Korea.
Aker was awarded a contract in July 2010 to supply a mooring system for the FPSO. Under the $24m contract Aker supplied 14 chain stoppers and three windlasses with a chain size of 165mm. In July 2010, APL was awarded a contract for providing the offloading system for the FPSO.
Technip subcontracted Aker Solutions in November 2010 to provide heating systems for the subsea equipment. Aker was awarded another $10.8m contract in December 2010 to provide tie-in and connector services for the flowlines and risers to be supplied by Technip.
In December 2010, Siemens won a contract to build the shoreside power supply system for the field.
In November 2011, the Offshore Division of Lankhorst Ropes was contracted to supply mooring lines for the Goliat FPSO by early 2013.
ABB installed a subsea power cable at the field under a $12m subcontract with Aker. The 1,065km-long cable, weighing 6,000t, will run from the Hammerfest substation to the Goliat FPSO. ABB was awarded the $110m contract in April 2010.
In February 2011, AGR Field Operations won a contract to provide maintenance and inspection services for the Goliat FPSO.
AGR Drilling Services was awarded a contract in June 2011 to deploy its cutting transportation system (CTS) to drill 22 wells at the field. Hyundai subcontracted Hamworthy in June 2011 to supply an inert gas generator system for the FPSO.
Posh Terasea provided a fleet of vessels, including Terasea Eagle, Terasea Osprey and Terasea Hawk to perform the station keeping and heading control duties of the FPSO.
Ramboll Group performed a winterisation study on the FPSO to evaluate its safety during offshore operations in harsh cold climate.
Other contractors include Rosetti Marino, Aibel, SAL, Trillini Engineering, Rina Services, Oceanira, Bureau Veritas, Multiconsult Group, Blucher, Kuehne+Nagel AS, Fjeld Consultant, Ulva Insulation Systems, TraceTeam, Frammarine and Semar.