BP Exploration has confirmed a 100 million bbl offshore extension of Wytch Farm oil field on the south coast of England.
The offshore extension of western Europe's largest onshore reservoir boosts Wytch Farm reserves to about 300 million bbl.
Options to develop the added reserves have been proposed, and BP now has the task of winning approval for the project in an environmentally sensitive area.
BP is in the final stages of a major expansion of the onshore portion of the field, about 20 miles east of Weymouth.
Facilities that will hike production to 60,000 b/d from 10,000 b/d are to start up in April or May. In addition, the project will produce 500 metric tons/day of LPG and 10 MMcfd of gas.
Wytch Farm facilities also will handle production from a small nearby reservoir. The U.K. Department of Energy approved BP's development of the 6 million bbl Wareham field, expected to produce about 2,800 b/d by yearend.
ONSHORE ENVIRONMENT
To win approval for the onshore part of Wytch Farm development, BP and partners ARCO British Ltd., Premier Oil Dorset Ltd., Kelt Exploration Ltd., Clyde Petroleum (Dorset) Ltd., and Goal Petroleum pic submitted a development program designed to minimize the effect of production facilities in a holiday area.
The region consists of bathing beaches, an enclosed harbor used by leisure and commercial shipping, and open heathland, the habitat of a number of rare birds and reptiles.
Meeting commitments to protect the environment is one reason for a substantial cost overrun on the project. The latest cost figure is 400 million ($668 million), about 100 million ($167 million) more than the original estimate.
OFFSHORE OPTIONS
BP opened its campaign to gain approval for offshore development by presenting six options to local authorities and groups without expressing its own preference.
The strategy is to allow consultation with these local groups to determine which of the options should be advanced to a development project.
The options consist of conventional and more innovative technology for the extension, which at its farthest point extends more than 6 miles from the coast. However, the thickest, most productive part of the Sherwood sands is within 21/2 miles of the shore.
Tapping the offshore reserves could cost as much as 200 million ($334 million) and require 30-40 wells. BP reckons that onshore well sites and extended reach wells could tap most of the reserves, although subsea water injection wells also would be required.
Offshore options range from conventional steel wellhead platforms to three alternatives for creating drillsites on artificial islands.
These include a dredged gravel island that could be landscaped or a concrete, gravity based island that would be built outside the area and ballasted onto the seabed.
Both types would be large enough to accommodate a land drilling rig.
The third island option is a smaller, gravity based, wellhead caisson that would be serviced by a jack up rig. However, more than one caisson drillsite would be required.
The final option is a series of multiwell silos sunk into the seabed. However, the sea is very shallow-only 15-30 ft deep-in this area. No project has attempted to install and service silos in such shallow water.
First response from the consultation process shows a local preference for the gravel island, mainly because it could be landscaped and offers the best facilities for containing an oil spill.
The offshore development project will use the existing onshore processing facilities.
BP estimates it could take as long as 2 years to complete the consultative process. By the time the project is complete in the mid-1990's, onshore production will be approaching the end of the 60,000 b/d plateau.
Offshore production will extend this plateau toward the end of the century.
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