Jeremy Beckman • London
Xcite Energy has submitted a development plan for Bentley, one of a cluster of heavy oil fields in the UK northern North Sea undergoing re-evaluation. Bentley, discovered in block 9/3b in 1977, holds reserves estimated at 550 MMboe, but its heavy viscous crude was long thought too challenging to bring to the surface. Xcite, however, applied modern production techniques to successfully test two new wells on the field in 2007 and 2010, with the latter confirming that a commercial development was feasible.
Bentley will be produced in two stages. The first, lasting three or four years, will involve the newbuild jackupRowan Norway serving as a drilling and production platform, with five producer wells in the field's core area and a single water injector.
On arrival at the surface, the produced fluids will be heated to 90-120°C (194-248°F) for water and sand separation, before passing through a first-stage separator to remove lighter gas bubbles, and then through centrifuges for further separation. Oil discharged from the centrifuges will be cooled to 90°C and subsequently transported via a short subsea pipeline to a floating storage unit for blending with a diluent crude to lower the viscosity.
Experience gained will be factored into design of the second-stage scheme, likely to be in place for 20 years. Here the jackup will be replaced by a fixed platform, with a second platform potentially added later on to recover oil from Bentley's southern area.
Shetland fields set for overhaul
West of Shetland, BP and its partners have approved a $4.8-billion redevelopment of the Schiehallion and Loyal oil fields, which together have delivered nearly 400 MMbbl of oil since 1998 through theSchiehallion FPSO. While a further 450 MMbbl remain to be produced, the floater has a limited lifespan, hence the decision to commission a new one from Hyundai Heavy Industries which should be installed in 2015. This will be 270 m (886 ft) long and 52 m (170 ft) wide, and able to process up to 130,000 b/d of oil and to store over 1 MMbbl. BP also plans to upgrade or replace existing subsea facilities to maximize oil recovery. All the new facilities should be operational in 2016.
In the same region, Total has successfully tested a new subsea well capping device commissioned by Oil & Gas UK's Oil Spill Prevention and Response Advisory Group to strengthen Britain's emergency response capability. Over a 10-day period in July, the device was transported to the offshore location in block 206/4, 75 km (46.6 mi) northwest of Shetland. There it was lowered by crane over the side of a service vessel onto a purpose-built landing base on the sea floor at a depth of 300 m (984 ft), designed to simulate a subsea well.
Cutting shears were deployed to sever a marine riser pipe, with ROVs discharging a subsea oil dispersant (a non-toxic, fluorescent dye). The capping system was locked onto the well and successfully activated, again using an ROV, with all the equipment later recovered, including the landing base.
Aldous Major opens potential North Sea play
Statoil may have a major new discovery in the southern Norwegian North Sea. The semisubmersibleTransocean Leader drilled the Aldous Major South structure in 112 m (367 ft) water depth in license PL 265, encountering a 65-m (213-ft) oil column in Jurassic sandstone. The initial assessment is 200-400 MMboe in place for this part of the prospect, with further upside to the south and to the north, where the rig was due to resume drilling last month.
Aldous Major South is 4 km (2.5 mi) west of Lundin Norway's Avaldsnes find in PL 501, which appears to be of similar size. The two fields are in communication, with a common oil/water contact, and a further 400 MMboe in prospect in the upper part of Aldous' productive interval. If proven, this could push combined reserves potentially to over 1 Bboe. If proven, this would be one of Norway's Top 10 oil finds, according to Statoil's Executive VP for Exploration Tim Dodson.
|Early last month, the crane vesselSaipem 7000 completed installation of the 7,000-metric ton (7,716-ton) steel jacket for Statoil's Gudrun platform in the Norwegian North Sea. The last of the 12 60-m piles was driven into the sea floor on Aug. 2. The jacket is a traditional design comprising two main structures, each weighing nearly 2,300 metric tons (2,535 tons), and connected by six horizontal frames and various bracings.|
Luno is still working towards submitting a plan this year for development of the 148-MMboe Luno field in the same region, in PL 338. This too will require a standalone facility, which will also take in production from this year's basement Tellus discovery, thought to be a northern extension of Luno.
Lundin and partners Talisman and Noreco have tabled a plan for the 22-MMbbl Brynhild (ex-Nemo) field in PL 148, which they aim to tieback to Shell's Pierce FPSO in UK waters. But Lundin has called a halt to work on the Krabbe accumulation in PL 301, due to uncertainty over its resources.
Ormen Lange subsea network extended
Norske Shell has placed a fourth subsea template on the Ormen Lange field in the Norwegian Sea. The water depth of 925 m (3,035 m) is unparalleled for a subsea installation in northern Europe, the company claims. Seabed conditions at this northern part of the field are also softer, and therefore more complex, than the central and southern locations of the earlier templates. Over 100,000 metric tons (110,231 tons) of stones had to be dumped to secure the 950-mt (1,047-t) structure and associated new pipelines.
Following installation of a manifold to control future well flow, the drillshipWest Navigator should be able to start putting in gas production wells in this northern segment later in the year.
DONG to address Siri weaknesses
Noreco has agreed to sell its 50% interest in the Siri field in the Danish North Sea to operator DONG Energy for $13 million. This will leave DONG free to pursue its preferred solution to rectify cracks in the Siri platform's underwater support structure, first noted in 2009. These caused production to be suspended for several months until a temporary repair could be implemented.
DONG estimates the cost of its long-term solution at $385 million, which will be spread over 2011 and 2012, and only partly offset by its increased share of production from Siri. Noreco will remain a partner in the satellite fields Cecilie, Nini, and Nini East.
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