Alpha Petroleum has lifted the lid on a new FPSO based development for the Cheviot heavy oil field in the UK sector of the North Sea.
Alpha has spelled out plans for a 26 well project with a target for first oil in 2021, which will have production of up to 35,000 boe/d in the first year.
Cheviot in UK blocks 2/10b, and 2/15a and 3/11b in the northern North Sea about 95km east of the Shetland Isles, is the former Emerald field, which produced between August 1992 and February 1996, when it was abandoned due to a high level of water production and low oil prices.
Now a new field development plan has been submitted to the UK's Oil and Gas Authority involving the use of a ship-shaped FPSO with oil storage and offloading by a shuttle tanker, after Alpha Petroleum acquired the Cheviot blocks from ATP Oil and Gas last year.
Alpha indicates that this new FPSO, which will be based on a modified tanker, will likely have a turret mooring system and will be connected to three subsea production centers via infield pipelines.
A total of 26 wells are planned; 20 of these will be oil producers in the Cheviot reservoir, one producer will tap a satellite Peel oil reservoir. Three further wells will be used for water injection and two more for gas injection. The development plan also includes possible later development of the Padon gas reservoir, which lies to the west of Cheviot.
Development drilling with a semi-submersible rig is scheduled to start in Q1 2019. Wells will be drilled in a continuous program until 2Q 2023. Installation and commissioning of pipelines and subsea infrastructure is due between 2020 and 2023, and the float in and installation of the Cheviot FPSO is planned for 3Q 2020 and first oil in 1Q 2021.
Cheviot has a heavy crude oil rated at 23° API, and has a high acid content – TAN 2.9.
The FPSO will be designed with living quarters and process equipment, and will be used to store the heavy Cheviot crude and export it via a tanker – because the acid content of Cheviot crude is unsuitable for pipeline export.
Up to 32 tanker visits are expected during peak production, declining to between two and four visits during the last years of production, when the water cut from the field is expected to reach up to 95%.
The field was discovered in 1978 by the 2/10a‐4 exploration well and was subsequently appraised by a further five wells between 1981 and 1985. Another two exploration wells, 2/10a‐6 and 2/15a‐9 discovered the Peel oil field and the Padon gas reservoir, respectively.
After first coming onstream, the floating production facility Emerald Producer was unable to handle the high level of water production and the field became uneconomic and ceased production in February 1996, after a total of 16m bbl of oil and 25 Bcf of gas was produced, representing just 7% of the total estimated oil in place, which was originally put at 36.9 MMcm (232 MMbbl).
After further evaluation of the field, Alpha indicates that Cheviot is now estimated to contain P50 reserves of up to 9.49 MMcm (59.7 MMbbl) of oil.
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