Athena is an abandoned oilfield located in UK Continental Shelf block 14/18B in the central North Sea at a water depth of 130m. It is situated in the Outer Moray Firth area.
The operator of the field, Ithaca (22.5%) bought the licence in 2005 in partnership with Dyas UK (17.5%), EWE Energie (20%), Trap Oil (15%), Spike Exploration (15%) and Zeus Petroleum (10%).
Development drilling and fabrication began in January 2011, and the final production well was drilled and fully cased in June.
Commissioning and First production was achieved in May 2012 after the completion of a fifth development well and commissioning of the BW Athena floating production, storage and offloading (FPSO) vessel. Ithaca terminated production from the Athena field in January 2016, due to a decline in oil output.
Athena was discovered in 1991. A total of ten exploration wells have been drilled in the block since 1978.
The reservoir is characterised by lower cretaceous upper leek sandstone within the Scapa unit. Overlying Scapa shelves seal and trap the sandstone to the north-west and north-east.
Athena was developed as a subsea tieback to FPSO BW Carmen. The field development plan was approved by the Department of Energy and Climate Change in September 2010.
The development plan includes drilling of six production wells and two water-injection wells. Four production wells and one water-injection well were drilled initially. Depending on the field performance and water requirement, two new production wells and one water-injection well will also be drilled.
Four production wells were drilled by re-entering the four appraisal wells drilled and suspended previously. Of these, wells 15A, 16 and 18 were re-entered initially, while appraisal well 17z was re-entered later either as a production well or as a water-injection well. The conversion to production wells were made by using downhole pumps.
Ithaca Energy conducted an environmental impact assessment for the project in assistance with Hartley Anderson.
BW Carmen is the FPSO that was used for the development of the Athena field. The FPSO was mobilised 2km south-west of the drill location. The FPSO owner, BW Offshore, operated the vessel at the field on behalf of Ithaca.
BW Carmen has an eight-point mooring system. It has eight cargo tanks to store crude oil and also has facilities for fluid processing. It can offload crude at a rate of 1,160t per hour.
The vessel was upgraded at a Dubai shipyard before being relocated to the Athena field. The upgrades included extending the vessel by 20m to accommodate a new submerged turret production system, adding a new water-injection module and installing the gas turbine generator Solar Taurus 60.
After the upgrades, the vessel was renamed BW Athena. Installation of all topsides equipment was completed in September 2011 and the FPSO was fully commissioned in 2012. The BW Athena FPSO was demobilised from the field as production from the Athena oilfield ceased in January 2016.
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