The U.K. Department of Energy has approved two more oil development projects in the North Sea.
In one, Conoco (U.K.) Ltd. will employ one of the largest subsea installations in the world in Lyell field.
In the other, Occidental Petroleum (Caledonia) Ltd. will develop 140 million bbl Saltire field with a conventional four legged steel platform installed about 4 miles southeast of the new B platform in Piper field.
Meantime, Shell U.K. Exploration & Production, operator for the Shell U.K. Ltd.Esso U.K. plc combine, has started oil production from its innovative Osprey subsea field development project in the northern U.K. North Sea. The 60 million bbl Osprey field, about 112 miles northeast of Sullom Voe terminal in the Shetland Islands, will have a production of 25,000 b/d.
LYELL DEVELOPMENT
Conoco's Lyell field, in Block 3/2 about 303 miles northeast of Aberdeen, will cost 156 million ($306 million) to develop. It is scheduled for start-up in late 1992, aiming for peak production of 18,000 b/d the following year.
Subsea facilities will consist of eight producing wells and five water injectors linked to a subsea manifold tied back to the Ninian southern platform 9 miles away by a 12 in. main production flow line, an 8 in. test line, and a 10 in. water injection line. Operations will be controlled from Ninian southern.
Lyell is a 1975 discovery with an estimated 400 million bbl of oil in place. Conoco said about 30 million bbl will be produced in the first phase while the viability of developing other areas of the reservoir is determined.
Well system equipment has been ordered from Cameron Iron Works. Conoco expects soon to order control equipment and award contracts for development drilling and offshore installation.
Conoco owns a 33.34% interest in Lyell.
Its partners are Chevron U.K. Ltd. and Oryx (U.K.) Energy Co. with 33.33% each.
SALTIRE PROJECT
Oxy said Saitire, in Block 15/17 about 110 miles northeast of Aberdeen, will cost 400-450 million ($784-882 million) to develop. The field is expected to produce 45,000 b/d of oil and 50 MMcfd of gas starting in second half 1992.
A 35,000 metric ton integrated drilling, production, and accommodation platform will accommodate 24 wells. Subsea water injection facilities will be installed 1.6 miles from the platform and linked through three flow lines.
Saltire will be linked to Piper Platform B by a 40 in. pipeline bundle containing a 10 in. oil export line, 16 in. gas export line, 8 in. gas lift import line, and 16 in. water injection import line.
The 40 in. bundle will be fitted with integrated towheads with underwater safety valves at each end.
Oxy holds a 36.5% interest in Saltire. Partners are Texaco Britain Ltd. 23.5% and Lasmo North Sea plc and Union Texas Petroleum Ltd 20% each.
OSPREY START-UP
Osprey's 190 million ($362 million) production system consists of two underwater manifolds linked to ShellEsso's Dunlin platform 4.3 miles northwest. Dunlin extends from Shell-Esso's Block 211/23a into Block 211/18a held by Deminex U.K. Oil & Gas Ltd., Santa Fe Minerals (U.K.), and Arco British Ltd.
Shell Expro said the most innovative part of the development is in reduction of the size and weight of the two subsea manifolds to the point that they could be installed from a floating drilling rig. The separate production and water injection manifolds are 1,148 ft apart with six production and five injection wellheads for deviated wells clustered closely around.
Water injection for Osprey will peak at 70,000 b/d. Treated water comes from a 10 in. line from the Dunlin platform, where control and process facilities for Osprey field are located.
Each manifold has facilities for eight wells. These include spare connections to enable future development work if required.
Production moves to dedicated Dunlin process facilities through an 8 in. pipeline. There is also an 8 in. test line.
Subsea control, monitoring, and facilities for chemical injection are provided through a composite electrohydraulic umbilical linking the platform and subsea equipment.
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