Norsk Hydro AS has started oil production from giant Troll field off Norway.
Production is from eight predrilled wells on North Sea Blocks 31/2, 31/3, 31/5, and 31/6.
Hydro has developed the western portion of the field using wells with long horizontal sections tied back to the world's largest concrete semisubmersible production unit, the Troll B platform.
First oil was received at the $2.9 billion Troll B platform Sept. 19. The first receipt of oil at the onshore Mongstad terminal via the $154 million Troll subsea pipeline occurred early Sept. 21, about 3 months earlier than planned.
Production rose to almost 190,000 b/d within 3 days of start-up. A total of 22 oil producers and gas injectors will be used for this development.
Oil reserves in West Troll oil province are estimated at 420 million bbl. Hydro recently announced a plan to develop a thin oil layer in West Troll's gas province.
A 13 m thick layer below Troll's giant gas cap is estimated to raise West Troll's oil reserves to more than 1 billion bbl of oil. The thin layer of oil has become recoverable through recent advances in well technology.
Hydro plans to use horizontal wells completed as subsea tiebacks to Troll B and a new production semisubmersible to develop the thin oil layer (OGJ, July 10, p. 30).
Meanwhile, Norske Shell AS is working to bring East Troll gas reserves on stream by means of the world's tallest production platform, Troll A. East Troll reserves are estimated at 45 tcf of gas.
Partners in the Troll license are Den norske stats oljeselskap AS 74.576%, Hydro 7.688%, Norske Shell 8.288%, Saga Petroleum 4.08%, Elf Aquitaine Norge 2.353%, Conoco Norway 1.661%, and Total Norge 1.353%.
Hydro is operator for the Troll oil project. Norske Shell is operator of the Troll A gas platform during construction, and Statoil will take over the platform once production begins.
Visund plan
Hydro has submitted to Norway's Ministry of Industry & Energy a plan for development and operation of Visund field on North Sea Blocks 34/8 and 34/7.
Total project investment is estimated at $1.16 billion. Production is to start in mid-1998 in 1,100 ft of water.
The plan calls for phased development of Visund, which holds reserves estimated at 305 million bbl of oil and 2 tcf of gas.
Oil will be produced using a steel floating platform with drilling-production facilities as well as living quarters.
Hydro plans to drill 21 subsea wells: 12 producers, seven gas injectors, and two water injectors. The wells will be tied back to the platform, which will have productive capacity of 100,000 b/d.
Visund partners are negotiating with owners of nearby Gullfaks oil field regarding possible use of storage and loading facilities at one of the Gullfaks platforms. Gullfaks is operated by Statoil.
The Visund group also is evaluating the possibility of storage and loading into a separate floating unit connected to the Visund production platform.
Produced gas will be reinjected into the reservoir at first, with sales gas production expected to begin in 2006-2010.
Project timetable for oil production facilities is expected to be about 30 months. That assumes final approval from Norwegian authorities early in 1996.
Partners in Visund are Statoil 65%, operator Hydro 12.6%, Conoco 9.15%, Elf 9.1%, and Saga Petroleum 4.2%.
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