Lancaster oilfield
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| Lancaster oilfield | |
|---|---|
  Location of Lancaster oilfield | |
| Country | United Kingdom |
| Region | United Kingdom territorial waters |
| Location | West of Shetland |
| Block | 205/21a, 205/22a, 205/26b and 205/22b |
| Offshore/onshore | offshore |
| Coordinates | 60°11′N 3°52′W / 60.183°N 3.867°W |
| Operator | Hurricane Energy |
| Field history | |
| Discovery | 2009 |
| Start of development | November 2016 |
| Start of production | June 2019 |
| Production | |
| Current production of oil | 13,300 barrels per day (~6.63×105 t/a) |
| Estimated oil in place | 3,333 million barrels (~4.547×108 t) |
| Producing formations | Naturally fractured Precambrian age granitic basement |
The Lancaster oilfield is an offshore oil field in Scottish territorial waters 100 kilometres (62 mi) west of Shetland and 170 kilometres (110 mi) north of mainland Scotland in water depths of around 155 metres (509 ft). It comprises licence blocks 205/21a, 205/22a, 205/26b and 205/22b in Licence P1368 (Central), all of which are fully owned by Hurricane Energy.[1] It is the first naturally fractured basement oilfield in the United Kingdom Continental Shelf to reach production.
Exploration well 205-21-1A was drilled in 1974 by Royal Dutch Shell. It discovered light oil in naturally fractured Precambrian age granitic basement but was plugged and abandoned.[2] This was the first well drilled by semi-submersible rig Ocean Voyager after construction. An astonishing feat West of Shetland in wintertime.
In 2009, Hurricane Energy drilled well 205/21a-4 much deeper into the naturally fractured basement and discovered a substantial column of light crude oil with 38° API and a flow rate of 1,367 barrels (217 m3) of oil per day. Subsequently, a sidetrack well, 205/21a-4Z, was drilled in 2010 which flowed light oil at 2,885 barrels (459 m3) of oil per day. The 205/21a-4 well was plugged and abandoned. The 205/21a-4Z well was suspended.
Well 205/21a-6 was drilled in 2014. This included a one kilometre horizontal section. It produced a natural flow rate of 5,300 barrels (840 m3) of oil per day. This increased to 9,800 barrels (1,560 m3) per day with an electric submersible pump ("ESP"). Both figures were constrained by surface equipment capabilities and it was reported that the well could deliver 20,000 barrels (3,180 m3) per day with a modest 120psi drawdown under production conditions.[3] The well had a very high productivity index[4] ("PI") of 160 stb/psi/d. It was suspended as a future producer.
Well 205/21a-7 was drilled in 2016 and produced 11,000 barrels (1,700 m3) of oil per day with an ESP. It was subsequently sidetracked as 205/21a-7Z to include a one kilometre horizontal section. This produced a natural flow rate of 6,520 barrels (1,037 m3) of oil per day or 15,375 barrels (2,444 m3) per day with an ESP, both of which were constrained by the test equipment used, and a very high PI of 147 stb/psi/d. It too was suspended as a future producer.[1][5]
Early Production System
In 2016, Hurricane committed to an Early Production System ("EPS") using the Aoka Mizu[6] Floating production storage and offloading vessel ("FPSO"), chartered from Bluewater Energy Services, for an initial six-year period with an option to extend to ten years.[7] This will be used to generate revenue and evaluate the reservoir properties over an initial testing period expected to take 6 to 12 months followed by a production period for the remainder of the duration. The results of the initial testing will inform decisions regarding potential full field development. The EPS utilises wells 205/21a-7Z and 205/21a-6. Revenue generated from oil sales will help to fund further activities in the Lancaster Field and the adjacent Halifax, Warwick and Lincoln fields.[1]
Reserves, contingent resources and initially in place volumes
The Competent Persons Report ("CPR") published by RPS Energy on May 8, 2017, provided the following estimates of reserves, contingent resources and initially in place volumes;[8]
- Reserves
- 1P: 28.1 million barrels (4.5 million cubic metres) of oil equivalent
- 2P: 37.3 million bbl (5.9 million m3)
- 3P: 49.3 million bbl (7.8 million m3)
- Contingent resources
- 1C: 129.1 million bbl (21 million m3) of oil equivalent
- 2C: 486.1 million bbl (77 million m3)
- 3C: 1,116.7 million bbl (178 million m3)
- Initially in place volumes
- Low estimate: 1,571 million bbl (250 million m3) of oil equivalent
- Best estimate: 2,326 million bbl (370 million m3)
- High estimate: 3,333 million bbl (530 million m3)
These estimates will be re-assessed during 2020 and 2021 taking account of the findings from the Early Production System. In July 2020, Hurricane announced that the prospective resources might be materially downgraded as a result of experience with the Early Production System. An updated Competent Person's Report is expected to be published before the end of the first quarter of 2021. A further update is expected to be issued with Hurricane's interim financial results in September 2020.
First oil
The Aoka Mizu FPSO arrived at the Lancaster field on 17 March 2019. Two days later, it was successfully hooked-up to the turret mooring system buoy.[9] On 11 May 2019 hydrocarbons began flowing into the processing system of the Aoka Mizu. Following a 72-hour production test during which the planned production rate of 20,000 barrels (3,200 m3) of oil per day was achieved, a press release announcing first oil was issued on 4 June 2019.[10] When announcing first oil, Hurricane Energy forecast that production for the first three months would be 9,000 barrels (1,400 m3) of oil per day and 13,000 barrels (2,100 m3) per day for the following three months giving a combined average of 11,000 barrels (1,700 m3) of oil per day for the first six months with production being constrained by testing activities.[11]
