Culzean Oil Field is located off around 230km off the coast of Aberdeen in the UK. (Credit: Keri Jackson from Pixabay)
Sembmarine delivered the PGM and two bridges for the Culzean Gas Field (Credit: Sembmarine SLP Ltd)
Culzean’s FSO vessel measures 52m in height and spans 243m in length. (Credit: A. P. MOLLER - MAERSK)

Culzean is an offshore gas condensate field located in the North Sea, around 230km off the coast of Aberdeen in the UK.

The high-pressure, high-temperature (HPHT) gas condensate field was discovered in 2008 by Maersk Oil, which was acquired by TotalEnergies in August 2018.

In August 2015, Culzean was approved for development by the UK Oil and Gas Authority. Installation of the facilities began in 2016 and production commenced in June 2019.TotalEnergies is the operator of the project with a 49.99% stake. BP (32%) and JX Nippon (18.01%) are the other project partners.

Culzean is expected to contain between 250 million and 300 million barrels of oil equivalent. The field can meet around 5% of the UK’s total gas demand with a plateaued production of 100,000 barrels of oil equivalent per day (boe/d).

The HPHT gas condensate field can produce 400 to 500 million standard cubic feet per day at peak.

Location and site details

Culzean is located in Block 22/25a (License P111) in the East Graben area of the Central North Sea. The location is around 145 miles east of Aberdeen. The water depth at the site is around 90m.

The field has two deep reservoirs situated 4,300m below sea level.

Project details

Culzean project includes six production wells, three platforms and a Floating Storage and Offloading (FSO) unit.

The three platforms, connected with bridges, are Wellhead Platform (WHP), a central processing facility (CPF) and a utilities and living quarters (ULQ) platform.

WHP is used for drilling and hydrocarbon production, while CPF serves as the centre to process and export produced gas and condensate. The ULQ is the crew’s living quarters that can accommodate 140 men.

The FSO vessel measures 52m in height and spans 243m in length, which is equivalent to three Airbus A380s.

Known as Ailsa, the FSO vessel can receive 25,000 barrels of condensate per day and store up to 430,000 barrels.

The FSO was delivered in 2018 and it can operate for 25 years continuously without dry-docking.

A Power Generation Module (PGM) was installed on the top of CPF.

The PGM module consists of three 7,500kw Dual Fuel Turbines and associated systems, a pedestal crane, workshops, and stores.

Process and utility fluids are carried from WHP to CPF bridge by 18 pipes and from CPF to ULQ bridge by ten pipes.

The interconnecting bridges also feature walkways and support for the routing of power and communications cables.

The produced gas condensate is stored in the FSO vessel for offloading by shuttle tanker.

The project development also features a produced water reinjection well (PWRI) and three replacement wells.

According to TotalEnergies, Culzean is the company’s most advanced digital offshore facility. The use of efficient drilling techniques and the optimisation of the supply chain have helped in reducing the cost of the initial budget by $500m, which represents 10% of the initial estimated budget.

In the design phase, a virtual reality model of the oil field was created for assessing risks and identifying solutions. The move also helped in optimising project infrastructure.

Culzean Project includes a Support and Monitoring of Assets in Real Time (SMART) room for collecting data, and managing production and maintenance work.

The SMART room has a range of digital tools for effective communication among onshore support crews, SMART room staff, and offshore operators. The crew is provided with hand-held devices for receiving information and expediting response during emergencies.

It took more than 7,000 people and 40 million man-hours to complete the project.

Contractors involved

KBR received the contract for Culzean field concept studies. It also conducted front-end engineering design (FEED) of the topsides for three platforms.

Maersk Highlander rig was used for drilling activity at the field.

England-based Sembmarine delivered the PGM and two bridges for the Culzean Gas Field. The top sides of the project were made at the Sembcorp Marine Admiralty Yard (SMOP) Admiralty Yard in Singapore.

Oglaend System delivered Mekano Support Systems, OE cable ladders, and SPB-RF cable trays for the project, while Hobbs Valve supplied Triple Offset Butterfly Valves (TOV), a zero-leakage solution.

Mane got a joint contract with another supplier to supply 150 workers for hook-up and commissioning works at the offshore platform over 12 months.

Emerson Process Management offered a range of project and support services from its UK headquarters in Leicester to support the automation of the gas condensate field.

DNV GL won a multi-service contract for the Culzean field development project that included Independent Competent Person (ICP) Verification, Independent Verification Body (IVB), Pressure Equipment Derivative (PED), and Explosive Atmospheres Directive (ATEX) services.

Modec carried out the engineering, procurement, construction, and commissioning of the FSO vessel.

Modec’s subsidiary SOFEC designed and supplied the Internal Turret Mooring System of the FSO.

PJ Valves (PJV) supplied 1,000 valves for the Culzean field.