Dunbar

Discovery and Production

• The Alwyn North Field, where the Dunbar project is situated, was discovered in 1975. Oil and gas production from Alwyn North began by the end of 1987.
• The Dunbar and Ellon fields, part of the Alwyn South Area, commenced production of their first hydrocarbons at the end of 1994.

Development Philosophy

• The development philosophy for the Dunbar project was to maximize the use of existing Alwyn North facilities and infrastructure. This involved a four-legged jacket with minimal topside processing facilities.

Infrastructure

• The Dunbar platform was developed using a tender-assisted drilling (TAD) concept, with the semisubmersible rig Sedco 706 bridge-linked to the Dunbar platform for the development drilling phase.
• Production from the Dunbar and Ellon fields is commingled and exported via a 22-km, 16-in. multiphase insulated pipeline to the Alwyn North platform, where receiving facilities were installed.

Wells and Drilling

• The Ellon Field was developed with twin subsea wells tied back to the Dunbar platform.
• A 20-well development drilling campaign was completed in 1998. Following this, eight additional potential targets were identified, including wells to target untapped panels and unswept areas of Dunbar Main, and wells to target recovery from Dunbar tight zones using multi-lateral and horizontal drains.
• Two of these wells were planned as appraisal wells for the as-yet-undeveloped Dunbar South panels, with one well featuring an extended reach profile (ERP) of 7,300 meters.

Production and Reserves

• Initial oil production from the Alwyn North Field was above 100,000 barrels per day (b/d), and the gas export capacity was 9 million cubic meters per day.
• After a short production plateau, it was recognized that oil production from Dunbar and Ellon would decline, prompting actions to reduce operating unit costs and increase production and reserves. This included increasing water injection into the reservoirs and drilling additional wells to target untapped areas.

Cost Management and Efficiency

• To manage costs, a systematic review of all opportunities and constraints was conducted. This led to actions such as reducing operating expenditures and negotiating new transportation and processing agreements, including a new Alwyn liquid export pipeline to the Shell-operated Cormorant Alpha platform.
• Despite the addition of new facilities, the operating budget for the entire offshore complex (including the existing Alwyn North twin platforms, the new Dunbar platform, and Ellon subsea facilities) was maintained at the same level as before the Dunbar startup.

Life Extension

• Various strategies were implemented to extend the life of the field. These included the use of Sulzer multiphase pumps to enhance production efficiency and extend the field's life.
• The project aimed to prolong the production plateau to 2005 and extend the expected life of the fields beyond 2015 through these new developments and cost-saving measures.

Commercial and Operational Agreements

• A new transportation and processing agreement was negotiated with the Brent pipeline system, and a new Alwyn liquid export pipeline was installed to provide a cost-effective transportation facility for the long term.

Overall, the Dunbar oil project is a testament to the innovative approaches and strategic planning used in the oil and gas industry to maximize field value and extend the life of production assets.