Andrew is located approximately 230 kilometres North East of Aberdeen and covers an area of 27 square kilometres, spanning licence blocks 16/27a and 16/28. BP discovered the field with its first well in 1974 and ConocoPhillips confirmed a westerly extension in 1975. The Andrew reservoir lies at a depth of some 2,430 metres below sea level and is contained within the Palaeocene. In addition there is an underlying lower Cretaceous gas reservoir, which has not been fully appraised. Twelve horizontal production wells and one gas re-injection well were originally drilled to tap the reservoir. Estimated recoverable reserves of:
- 150 million barrels of oil and natural gas liquids (NGLs).
- 245 billion cubic feet of associated gas.
This compares with Annex B estimates of:
- 120 million barrels of oil.
- 135 billion cubic feet of gas (NGLs).
Andrew Development Philosophy
After the discovery, commercial innovations allowed Andrew to be developed into a viable field. Andrew was eventually developed by an Alliance of BP and seven contractors, which tied financial rewards firmly to the final cost of the project. The final project cost around #290 million and the savings were shared among the Alliance partners. The total project costs including drilling and pre-operations were around #432 million. The Andrew Alliance consisted of BP, Brown & Root, Santa Fe, Saipem, Highlands Fabricators, Allseas, Emtunga, and Trafalgar House.
- Production began in 1996 and field life is expected to be around 18 years.
- At peak production Andrew produced around 80,000 barrels of oil per day.
- In 2002 production had declined to 33,000 barrels per day and 40 million standard cubic feet of gas per day, remaining gas is re-injected to maintain reservoir pressure.
- The oil is exported through a 10-inch diameter, 16-kilometre long pipeline to the Brae-Forties system.
- The gas is exported through an 8-inch diameter, 44 kilometre long pipeline to the Central Transmission System (CATS).
The Original Andrew Development
The Andrew development consists of:
- A single fixed platform.
- A piled steel jacket supporting an integrated deck with production, drilling and accommodation facilities.
The steel structure consists of:
- A lift installed, four legged jacket weighing approximately 7,500 tonnes.
- Lift weight for the integrated deck is approximately 10,400 tonnes.
- A design operating load of 15,000 tonnes.
- Permanent accommodation is provided for 80 people.
- The Andrew topsides include facilities to operate the nearby Cyrus and Farragon subsea satellite development.
The Future for Andrew
In 2011, a new Andrew Area Development (AAD) project was sanctioned. The sponsoring partners were BP, JX Nippon and Talisman-Sinopec. The overall project objective was to develop the hydrocarbon resource in the Kinnoull field while positioning to develop future reserves in the Andrew Lower Cretaceous reservoir and Arundel field. The Kinnoull field is an oil reservoir that lies approximately 25 km northeast of the Andrew platform and 4.6 km from the UK/Norway boundary in the UKCS Block 16/23a at a water depth of 103 m. The AAD project scope comprises drilling three wells into the Kinnoull reservoir and production via a new subsea bundle pipeline system to a new module with horizontal three phase separator on the Andrew platform. The scope also covers modifications to the existing Andrew facility in order to allow the Topsides to receive the new module and handle and process fluids from the Kinnoull reservoir. These include:
- New 700 tonnes prefabricated separation module
- New Hydraulic Power Unit (HPU)
- Structural modifications
- New topsides process pipework to allow integration of new and old systems
- New riser caisson at Andrew
The project started up in 4Q 2014. It will extend the life of the Andrew platform beyond 2020 and provide a new CNS hub for future tie-backs like Arundel.