BP, Chevron/Conoco start up key U.K. fields

BP Exploration Operating Co. installed twin platforms in Marnock field on U.K. North Sea Block 22/24a, to act as the hub of its seven-field Eastern Trough Area Project (ETAP) development. Quarters and utilities are housed on the 11,300 metric ton platform to the left in the photograph. These are separated from the bridge-linked 23,400-ton production platform that holds wellheads, process modules, gas compression equipment, and flare stack. Photos courtesy of BP.

BP's Block 22/20 Mungo field wellhead platform is part of the ETAP development. Mungo was the first of the seven fields in ETAP to be brought on stream. The platform weighs 4,000 tons and is shown here overshadowed by the Santa Fe Monarch heavy-duty jack up rig, which is being used for development drilling. [17,190 bytes]
The Schiehallion FPSO is the second such floating production, storage, and offloading (FPSO) ship to be deployed in the U.K.'s West of Shetland area, following BP's Foinaven FPSO, which began oil production last November. The Schiehallion ship has double-sided storage tanks with capacity to hold a total of 900,000 bbl of oil and has a displaced gas-recycling system to reduce volatile organic compound emissions when the ,cargo is being offloaded into a shuttle tanker. [7,429 bytes]

BP Exploration Operating Co. Ltd. and a joint venture of Chevron U.K. Ltd. and Conoco (U.K.) Ltd. have brought key U.K. offshore fields into production.

BP announced first oil from its Eastern Trough Area Project (ETAP), a group of seven fields in the central North Sea, immediately following start up of Schiehallion field in the West of Shetland area.

Meanwhile, Chevron/Conoco's Britannia Operator Ltd. (BOL) joint venture began gas and condensate production in the central North Sea'sBritannia field, the U.K.'s largest offshore development in several years (see related article in Offshore Northern Europe special report, p. 49).

ETAP

BP's ETAP fields were developed with a twin-platform central processing facility along with a wellhead platform and five subsea satellites. The fields are spread over an area roughly 35 km long by 30 km wide, where water depths are 85-95 m, centered around the central processing platforms in Marnock field on Block 22/24a.

BP is operator of four of the ETAP fields-Marnock, Mungo, Monan, and Machar-while Shell U.K. Exploration & Production is operator of three subsea satellites: Heron, Egret, and Skua (OGJ, Jan. 22, 1996, p. 21).

Block 22/20 Mungo was the first field brought on stream, on July 18. Mungo output has been stabilized at 30,000 b/d of oil, and work has begun on commissioning ETAP's gas processing plant.

BP said more fields will be brought on stream over the next 2 months, with production expected to build to a peak of 210,000 b/d of oil and 360 MMcfd of gas during 1999.

Chris Rhodes, BP's ETAP and central North Sea business unit leader, said the £1.6 billion ($2.6 billion) ETAP project was one of the most significant North Sea developments in more than a decade.

"We do not believe a multifield development as complex as ETAP has ever been tried before," said Rhodes. "Production was originally scheduled to start in autumn 1998, and the ETAP alliance has delivered first oil some 2 months ahead of schedule.

"We have faced a variety of challenges including: high-temperature, high-pressure reservoirs; technically complex wells; distant subsea tie-backs; and the need for highly flexible processing plant on the central processing facility."

Marnock field participants are: operator BP 62.05%, Shell U.K. Ltd. 13.5%, Esso Exploration & Production U.K. Ltd. 13.5%, and Agip (U.K.) Ltd. 10.95%.

Mungo and Monan field interests are: operator BP 69.92%; Total Oil Marine plc 12.43%; MOC Exploration (U.K.) Ltd., a unit of Mitsubishi Oil Co. Ltd., 5%; and Murphy Petroleum Ltd. 12.65%.

Heron, Skua, and Egret are owned outright by the 50-50 Shell/Esso joint venture, of which Shell is operator, while Machar field is owned outright by BP.

Schiehallion

BP's Block 204/20 Schiehallion field was developed with a floating production, storage, and offloading (FPSO) ship gathering oil from four seabed manifolds.

The first well has stabilized at a rate of 30,000 b/d, and BP expects to bring 29 wells into production for development of Schiehallion and the overlying Loyal field.

Schiehallion reserves are estimated at 340 million bbl of oil, while Loyal reserves are pegged at 85 million bbl. Peak production is expected to be 154,000 b/d of oil, with storage capacity for 900,000 bbl on the ship.

The £1 billion ($1.6 billion) Schiehallion development is only the second field to be brought on stream in the U.K.'s West of Shetland play. The development concept is similar to the earlier Foinaven, although Schiehallion's development has not been so marked by mishaps (OGJ, Dec. 8, 1997, p. 21).

Schiehallion and Loyal oil will be collected every 5-6 days at peak by the dedicated Loch Rannoch shuttle tanker, for delivery to Sullom Voe oil terminal in the Shetland Islands. Loch Rannoch is currently being fitted out and is due to be delivered in August. Meantime, the Nordic Savonita tanker has been chartered to offload oil from the Schiehallion FPSO.

Schiehallion participants are: operator BP 33.35%, Shell 33.35%, Amerada Hess Ltd. 15.669%, Statoil (U.K.) Ltd. 5.877%, OMV (U.K.) Ltd. 5.877% and Murphy 5.877%. Loyal interests are operator BP 50% and Shell 50%.

Britannia

The Britannia platform is likely to be the last fixed platform to be used in a U.K. development. It comprises a 19,000-metric ton jacket and 28,600-ton topsides.

In an unusual approach for the U.K. offshore theater, the field was developed jointly, and BOL was set up with personnel from Chevron and Conoco to oversee the project. The field was developed under an alliance to reduce costs (OGJ, Dec. 26, 1994, p. 30).

BOL said Britannia is the largest field developed under U.K.'s Cost Reduction Initiative for the New Era program, which enabled a 20% cost reduction from the original development budget of £1.65 billion ($2.7 billion).

The platform has capacity to produce 650-740 MMcfd of gas and 50,000 b/d of condensate. Estimated field reserves are 2.6 tcf of gas and 140 million bbl of condensate. Field life is expected to be 30 years.