Buckland

Location and Field Description

The Buckland field is located in the North Sea and is the third subsea field to be processed by the central Beryl A production platform.

Development Strategy

Due to economic concerns and the high costs associated with Floating Production, Storage, and Offloading (FPSO) units, the operators opted for a subsea development strategy. This decision was driven by the fact that subsea projects often deliver oil below budget and ahead of schedule.

Well Scheme and Infrastructure

The project involves a five-well subsea scheme, which includes:

• Five producer wells
• Two water injector wells for pressure maintenance
  • One injector well for the north and central parts of the field
  • One injector well for the southern part of the field

The wells are tied back to the Beryl A platform through a bundled flowline system.

Bundle Composition

The bundle consists of:

• Three 8-inch diameter production flowlines
• A 12-inch water injector line
• A 4-inch gas lift line
• Chemical and injection controls tubing
• An electric control umbilical

The overtrawlable carrier pipe is 42 inches in diameter and 15 mm thick, but it is swaged down to 17 inches for the southern section of the field, where only one production flowline and one water injection line are required.

Completion and Equipment

All producer wells have monobore completions. To mitigate scale formation, a chemical injection mandrel is installed to permit continuous downhole scale inhibitor injection. The completion equipment, aside from the carbon steel tubing string, is interchangeable with equipment on the production wells. Individual Christmas trees are completed within individual manifold guide bases, and cage-like structures are installed to protect against dropped objects and trawler fishing.

Water Injection System

Due to the high barium and strontium content in the Buckland reservoir, seawater cannot be used for water injection to avoid plugged formation pores and corrosion scaling. Instead, sulfate-free water is drawn from a shallow aquifer well beneath the Beryl A platform using a Centrilift electrical submersible pump (ESP).

Processing and Production

The fluids from Buckland are brought to the Beryl A processing facilities via the bundled flowlines. At peak production, Beryl A will handle:

• 30,000 barrels per day (b/d) of oil
• 40,000 million cubic feet per day (MMcf/d) of gas
• 30,000 b/d of produced water from Buckland

The processing involves a dedicated production train with two existing separators: a two-phase separator for oil/water and gas, followed by a three-phase atmospheric separator after fuel gas-fired heating to treat the produced water. This segregation is necessary to avoid scale formation when commingling Buckland and Beryl production fluids.

Project Timeline and Approval

The £160 million development plan gained government approval in May 1998. The project was fast-tracked to realize its value as soon as possible, with first oil from Buckland expected in October of the same year. However, the plan was modified following the reinterpretation of a 3D seismic survey conducted over Buckland in 1997.

Additional Exploration

One well drilled in the northwest part of the field serves as an appraisal well, which could potentially increase the overall reserves by several million barrels if successful. Rig operations were suspended to allow the bundle installation to proceed, with the well expected to reach total depth in the fall.