The Bittern Development is located offshore UK. (Credit: Subsea7)
The offshore field was discovered in 1996. (Credit: Asset Guardian)
It commenced production in April 2000 via a tie-back to the Triton FPSO vessel. (Credit: © Imrandd)

Bittern is an offshore producing oil and gas development located in the Central North Sea of the UK.

The offshore field was discovered in 1996. It commenced production in April 2000 via a tie-back to the Triton Floating Production Storage and Offloading (FPSO) vessel.

Bittern is operated by oil and gas exploration and production company Dana Petroleum. The UK-based firm is a subsidiary of the Korea National Oil Corporation.

Location of Bittern Field

The Bittern Field is located in Block 29/1a and Block 29/1b in the UK Central North Sea at a water depth of around 90m.

The site is situated 22km southeast of the Triton FPSO and approximately 190km east of Aberdeen, a port city in northeast Scotland.

It contains a light 39⁰API oil with an initial gas cap.

Ownership Details

Initially, Bittern field stakeholders included Dana Petroleum, Shell, Endeavour and ExxonMobil.

Following a series of ownership changes, Bittern development partners included Tailwind Energy Holdings (64.63%), Dana Petroleum (E&P) (32.95%), and Waldorf Production (2.42%). Dana Petroleum has been the operator of the development since 2018.

In December 2022, Serica Energy signed an agreement to acquire the entire shared capital of Tailwind Energy Investments from Tailwind Energy Holdings.

The cash-and-stock deal, which closed in March 2023, comprised issuance of more than 111 million ordinary Serica shares and £58.7m in cash.

As part of the transaction, Serica earned 64.63% working interest in Bittern.

Bittern Field Development

The Bittern Development has five production wells, two water injection wells and a regional aquifer.

The infrastructure includes two seven-slot manifolds, four 10-inch production wells, a 12-inch water injection pipeline, and a 4-inch gas lift pipeline.

The wells of the offshore development are connected to the Triton FPSO via a subsea-tieback.

The water injection and gas lift pipelines connect Triton FPSO injection riser base in the UK continental shelf (UKCS) to Bittern field Drill Centre B manifold (DCB) in block 29/1.

Bittern produces by waterflood, an oil recovery technique that uses non-potable water for re-injection into the reservoir to maintain reservoir pressure.

Between 2019 and 2022, the project recorded multiple well interventions and drilling of a sidetrack well. As part of a Triton area drilling campaign, another sidetrack well was drilled in 2024 using the COSLInnovator rig.

In 2022, Bittern had a gross production up to 14,000 barrels of oil equivalent per day.

Triton FPSO

Triton FPSO is located in Block 21/30, approximately 120 miles east of Aberdeen. The vessel is operated by Dana since 2012.

It produces oil and gas from the Bittern, Clapham, Pict, Saxon, Guillemot West and North West fields. These fields are tied back to Triton via subsea facilities.

The FPSO is a Korea-built double hull tanker. It was modified in the Sembawang shipyard, Singapore Area subsea facilities.

The joint venture (JV) partners of the facility are Dana Petroleum (52%), Tailwind Mistral (46%) and Waldorf Production UK (2%).

The Triton FPSO was shut down by Dana Petroleum from early July to mid-September 2023. It was supported by a six-month walk-to-work campaign.

Key activities that were carried out included structural repairs and fabric maintenance work to extend the life of Triton.

Recent Contracts

In June 2024, Subsea7 secured a contract, worth between $50m and $150m, from Dana Petroleum for the Bittern Development.

The scope of the contract includes project management, engineering procurement construction and installation (EPCI) of the 22km long 12-inch water injection pipeline. The work also includes associated subsea structures and tie-ins at the Triton FPSO and the Bittern field.

Semi-submersible drilling rig COSLInnovator, used in the Triton area drilling campaign, is operated by COSL Drilling Europe. The rig is designed to operate in water depths up to 750m in harsh environments.