The Finlaggan gas condensate field will be developed as a tie-back to the Britannia platform. Image courtesy of ConocoPhillips United Kingdom.
The Finlaggan field was appraised by an appraisal well drilled by the Transocean Sedco 704 drilling rig. Image courtesy of Zennor Petroleum.
The Finlaggan field is located in Block 21/05c offshore Aberdeen in the UK central North Sea. Image courtesy of Zennor Petroleum.

Finlaggan gas condensate field is located in Licence P2013, Block 21/05c of the UK continental shelf (UKCS). The central North Sea field is being developed as a two well subsea tie-back to the Britannia platform.

Zennor Pathway is a wholly-owned subsidiary of Zennor Petroleum and 100% owner and operator of Finlaggan. The company has signed a construction and tie-in agreement with the Britannia Operator, awarded the subsea installation contracts to TechnipFMC and commenced drilling the development wells.

Formal Oil & Gas Authority (OGA) FDP approval for the project was awarded in October 2018.

The offshore construction works are expected to begin in early-2019, with first production planned for Q4 2020. The Finlaggan field is expected to have a peak production rate of 115 million standard cubic feet per day (Mmscfd) of gas and 8,000 barrels per day (bpd) of condensate.

Finlaggan gas condensate field discovery, geology and reserves

The Finlaggan gas condensate field was discovered in 2005 by ConocoPhilips. The discovery well, 21/5a-6Z, encountered a 169ft-long hydrocarbon column in the lower Cretaceous sands.

The hydrocarbons accumulated at the field are trapped in the structural reversal, where the reservoir pinches out in an up-dip direction.

Finlaggan is estimated to hold 27 million barrels of oil equivalent (Mboe).

Finlaggan offshore field appraisal

The lower Cretaceous sands have historically been difficult to seismically image. However, Zennor reprocessed the seismic data in 2015 with an innovative migration in the form of Generalised Radon Transform. This better imaged the Finlaggan trap leading to appraisal drilling in 2016.

One appraisal well named 21/5c-7 and side-track 21/5c-7Z were drilled by the Transocean Sedco 704 drilling rig in July 2016. The two wells successfully appraised the lower Cretaceous gas condensate accumulation of the Finlaggan field.

“The Britannia platform is located in Block 16/26 in the UKCS, approximately 17km north-east of the Finlaggan field.”

The appraisal well 21/5c-7Z was stem-tested and flowed at the surface equipment constrained rate of 40Mmscfd of gas and 3,120bpd of condensate.

Finlaggan gas condensate field development details

The Finlaggan development plan includes a subsea manifold and two production wells, which will be tied-back to the Britannia platform operated by ConocoPhillips and controlled through an umbilical.

The development wells are being drilled using the Transocean Paul B Loyd Junior semi-submersible drilling rig from a single surface location. Zennor began drilling the first development well in July 2018.

The production wells are expected to be drilled and completed within a span of 90 days each. The development wells will then be suspended until the installation and completion of the subsea infrastructure.

Infrastructure and processing

The gas and condensate produced by the field will be exported to the Britannia platform through a production pipeline for processing. The processed gas and condensate from the Britannia platform will be exported to the shore using existing infrastructure.

The 20km production pipeline will be heavily insulated with a pipe-in-pipe construction in order to maintain the temperature of the fluid and avoid flow assurance issues. The inner pipe will have a diameter of 10in, while the outer pipe will have a diameter of 14in.

The subsea infrastructure to be installed at the field will have a design life of 15 years, whereas the field is anticipated to have an economic life of seven years.

Financing for Finlaggan field development

Zennor received a £170m ($195m) Senior Secured Term Loan Facility to fund the Finlaggan development in October 2018.

Societe Generale, London Branch to BNP Paribas, DNB (UK) Limited and Nedbank Limited structured, underwrote, and syndicated the loan facility, wherein Societe Generale also acted as mandated lead arranger. Investec Bank and Barclays Bank are the lead arrangers of the loan facility.

Britannia platform details

The Britannia platform is located in Block 16/26 in the UKCS, approximately 17km north-east of the Finlaggan field. It processes oil, condensate and gas from different fields located in its vicinity.

The gas produced by the facility is exported through a pipeline to the St Fergus Scottish Area Gas Evacuation (SAGE) terminal, while the condensate is exported through a pipeline to the Unity platform and further connected to the Forties Pipeline System (FPS).

The platform has an oil export capacity of 67,800bpd, gas compression capacity of 740Mmscfd, gas export capacity of 740Mmscfd, gas lift capacity of 30Mmscfd and produced water handling capacity of 51,600bpd.

Contractors involved

The company manages all of the main procurement activities itself, with a range of drilling service and equipment providers involved in the current development drilling operation where well engineering support is being provided by Petrofac.

The subsea trees have been manufactured by BHGE, and subsea front-end engineering design (FEED) studies were undertaken by Xodus. The subsea pipeline and umbilical manufacture and installation contracts have been recently awarded to TechnipFMC.

The environmental impact assessment report for the Finlaggan field development was prepared by Orbis Energy. The seismic reprocessing leading to development was completed by Seismic Image Processing.