Central North Sea
The Affleck oil field is located in Central Graben Block 30/19a in the Central North Sea in a water depth of 72m. The field is approximately four miles from the UK/Norwegian line, 200 miles from the Scottish Coast and 17 miles from the Janice field.
The Affleck field is operated by Maersk Oil, which has an interest of 66.67%. Talisman North Sea holds the remaining 33.33% stake. The first oil was produced from the well in August 2009 and its expected life is estimated to be 13 years.
Discovery and geology
The Affleck field was discovered by Shell in 1974. The oil is produced from a chalk formation. The field comprises a domed tor chalk reservoir, and is a four-way dip closed structure on the salt diapir.
The chalk reservoir has been drilled with horizontal wells. Maersk Oil has employed Noble TVL drill rig to complete development drilling.
The Affleck field development involved two sub-sea horizontal production wells. The wells are tied back to the Janice Floating Production Unit (FPU) located in Block 30/17a through a new 28km production flowline.
The development also included construction of a new gas export spurline to the offshore installation known as the Clyde platform. The platform is located over the Clyde oil field.
Janice has undergone modifications to process and export the Affleck production line. Topside modifications were done to the Clyde platform. Sub-sea manifold, umbilical and control systems have been developed for Affleck to support up to four production wells.
The sub-sea installation service contract was awarded to Technip Offshore UK for tying back the Affleck field to Janice. Under the contract, the 28km pipe-in-pipe flowline and associated umbilical and risers have been installed.
Technip has also managed the design, manufacture, fabrication and installation of two SSIV structures and an 80t manifold. A connection from the existing tee on the Janice gas export into the Clyde platform has also been installed.
Floating production unit
The Affleck field was developed with the existing FPU Janice A in Block 30/17a. The unit is placed on Aker H3.2 semi-submersible vessel, previously known as the West Royal. Earlier, it was used as a floating accommodation vessel and later modified for oil and gas production.
The structure’s engineering, construction and support services have been provided by the Aker Kvaerner Offshore Partner. The structure weighs 18,000t.
The FPU is capable of exporting 66,340 bopd oil and 40-60MMscfd gas. It has been modified for the processing and export of Affleck production line.
The Janice A platform separates oil through a single, three-phase separator. The separated oil undergoes cooling, boosting and metering process. Further, it is exported to Norpipe system through the J-block spur.
The gas is released into compression train, water produced in the process is cooled and dispatched to the production water-handling facility. The FPU also houses a two-phase test separator. The unit’s extra processing capacity supports the future developments.
The production chamber of Affleck comprises two sub-sea horizontal production wells that are tied back to the Janice A FPU. The FPU has been upgraded for the Affleck field in 2008.
The production was planned in July 2008, but delayed due to the FPU shutdowns. The production of oil began in August 2009.
The oil produced in the field is exported through the existing Janice pipeline into Norpipe trunkline system, then to Teesside in north-east England. The gas is transported via existing tees on the Janice and Judy export pipeline, via the Clyde and Fulmar facilities, to the SEGAL trunkline terminating at St Fergus in eastern Scotland.
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