The Captain field lies approximately 90 miles (145 km) north-east of Aberdeen, Scotland, in the Outer Moray Firth, in water depths of around 346 feet (105.5 m).
Discovered in 1977 in Block 13/22a, the Captain field achieved first production in March 1997, thanks to key technology developments in horizontal drilling and down-hole pumps in well bores.
The field includes a wellhead protector platform and bridge linked platform connected to a floating production, storage and offloading (FPSO) vessel and two subsea manifolds tied back and connected to the platforms by a suite of pipelines.
Captain crude oil is offloaded from the FPSO offloading vessel to a dynamically positioned shuttle tanker and transported to customers. Captain gas is exported (and imported) via subsea pipeline to the Frigg UK Gas Transportation System and then on to St Fergus gas terminal.
In 2020, daily production averaged 25,520 barrels of liquids and 3.0 million cubic feet of natural gas.
Ithaca Energy continues to implement projects designed to sustain production and increase recovery at Captain. This includes active platform and subsea well in-fill drilling and completion programmes targeting key areas of the reservoir. Continued development drilling is expected through the next decade.
A key project designed to increase recovery at the field is the Captain Enhanced Oil Recovery (EOR) project. As the most advanced polymerised water injection project in the UK North Sea, Ithaca Energy is using this innovative EOR technology to breathe new life into the billion-barrel field.
Polymer EOR has been trialled at the Captain field since 2010 to assess its potential and develop the best approach to any future deployment. This approach enabled plans to be to fine-tuned prior to progressing the project post sanction in September 2017.
The brownfield expansion has centred on the existing Captain infrastructure, located in a segment of the field supported by the existing platforms, known as Area A. The scope includes polymer injection in up to six long-reach horizontal wells, several brownfield work scopes, and the bulk provision of polymer designed for the specific reservoir conditions at Captain. The project has been utilising polymer for 2 years and performance is trending as expected.
Learnings from this first stage were used to inform the decision for stage 2 which involves the expansion of EOR into the subsea areas of the field.
For many years, the Captain field has been under waterflood, meaning a lot of effort has been focused on water production and treatment. However, with bypassed oil remaining in place due to the way waterflood results in a “coning” effect in the reservoir, EOR presents an opportunity to unlock significant potential by reducing the mobility contrast between the polymerised water and viscous oil.
A series of pilots demonstrated that Captain’s reservoir conditions – pressure, temperature, type of rock and oil properties – were right for polymer EOR.
Captain EOR is a prime example of how technology can help increase the economic viability of smaller and more complex fields, develop more cost-effective solutions and better use data to drive improved decision making.
Captain is operated by Ithaca Energy (UK) Limited (85 percent); Dana Petroleum (E&P) Limited holds a 15 percent non-operated working interest in the field.