BP Exploration Operating Co. Ltd. has completed a well with an extended reach of 5,000 m in its Wytch Farm oil field in Dorset, U.K.
The well is claimed by BP to be a world record horizontal displacement for a shallow well, having a true vertical depth of 1,530 m.
The F19 well is the second extended reach well in the field. It was drilled from an onshore site on the Goathorn Peninsula into the field's Sherwood reservoir which extends under Poole Harbour into Poole Bay.
Wytch Farm holds estimated reserves of 300 million bbl in two reservoirs.
Bridport reservoir lies 900 m below the surface and holds about 30 million bbl of oil. The reservoir is accessible from onshore using conventional drilling techniques.
Sherwood reservoir is believed to hold 170 million bbl in its onshore section and another 100 million bbl offshore.
BP originally proposed depleting Sherwood reservoir's offshore reserves from an artificial island built 1 mile offshore in Poole Bay. The island scheme was opposed by environmentalists.
BP withdrew its plan in December 1991 and replaced it with the accepted plan based on extended reach drilling from onshore sites. The company said the decision was based on economic grounds.
An artificial island development was budgeted at 180 million ($330 million). A cost of 80 million ($150 million) was estimated for development using extended reach wells (OGJ, Jan. 6, 1992, p. 24).
WELL DETAILS
F19 well was the second of four extended reach wells to be drilled from Wellsite F on the Goathorn Peninsula. The angle was built up at a maximum 2.5/30 m, reaching 80 from vertical at target depth.
About 1,200 m of reservoir interval was cut. BP expects this to allow production of 15,000 b/d of oil from the well.
The first extended reach well was F18, spudded last Apr. 15 and eventually attaining 3,800 m extended reach. F18's angle was built rapidly at 4/30 m to enter the reservoir at 70.
The angle of the well was increased to horizontal within the reservoir. This yielded 1,000 m of exposed interval, leading to production of 15,000 b/d.
More than 60 wells have been drilled in Wytch Farm field since a license was awarded in 1973. Bridport reservoir was discovered in 1974, while Sherwood reservoir was found in 1978.
First production was from the Bridport reservoir in 1979, while first oil was produced from Sherwood in 1980. Total production is about 73,000 b/d at present. Wytch Farm produced its 100 millionth bbl of oil last October.
Ten more wells are planned to deplete the offshore reservoir section, some requiring step outs of about 6,000 m.
NEW WELLSITE
BP has won planning permission to build a new drilling pad, Wellsite M, from which the additional 10 extended reach wells will be drilled.
Wellsite M is to be built alongside the F site and separated by a screen of trees. The site is currently covered by trees. BP said it will take 6 months to prepare for drilling.
Meanwhile, a BP official said the rig will be moved from the F19 well to spud a third extended reach well. The F20 well is expected to have a 5,500 m horizontal displacement.
A fourth extended reach well will be drilled from Wellsite F, with completion scheduled for second quarter 1994.
All Wytch Farm's extended reach wells are to be drilled by the Deutag T47 rig, owned and operated by Deutag Overseas (Curacao) NV, Aberdeen. The rig is said to be the largest currently operating in the U.K.
The rig is 60 m high and was originally built to drill 7 m diameter mine shafts to depths of 12,000 m. A 5 month conversion program, completed last March, was carried out by Deutag at its Bad Bentheim base in Germany.
Wytch Farm field partners are operator BP 50.475%, ARCO British Ltd. 17.334%, Premier Consolidated Oilfields plc 12.381%, Clyde Petroleum (Dorset) Ltd. 7.429%, Purbeck Exploration Ltd. 7.429%, and Goal Petroleum plc 4.952%.
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