Norske Conoco AS has won Norwegian government approval to develop Heidrun oil and gas field in Haltenbanken area off Central Norway with the world's first concrete hulled tension leg platform.
The field, with reserves of 756 million bbl of oil and 1.6 tcf of gas, is scheduled to go on stream in third quarter 1995. Production will rise to a peak of 200,000 b/d.
In other action off Northwest Europe:
- Amoco Netherland Petroleum Co. plans a $400 million gas development program on Blocks P/15 and P/18 in the Dutch North Sea. Initial production is to plateau at about 250 MMcfd, although the facility is designed to handle 500 MMcfd.
- Texaco North Sea shut down its Tartan platform in the U.K. North Sea and evacuated personnel after a gas leak occurred in an insulation spool on the gas export riser. Texaco said the subsea safety valve was closed immediately and the riser completely depressurized to eliminate possibility of any further gas escape.
- Den norkse stats oljeselskap AS (Statoil) will use a new concept in flare stack design for Sleipner gas development in the Norwegian North Sea.
- Norsk Hydro AS let contract for pipeline work related to its Oseberg field development in the Norwegian North Sea.
GAS DECISION DEFERRED
A decision on how associated gas from Heidrun field will be handled was deferred for a year while the Norwegian government fine tunes its environmental policy.
Conoco and Statoil want to use associated gas as a feedstock for an onshore methanol plant. Fears about the level Of CO2 emissions from the plant generated an alternative project to reinject the gas into a water filled reservoir in the Heidrun area.
As soon as approval for field development was given, Conoco issued four preengineering contracts for the 19 billion kroner ($3.28 billion) project.
For the first time in the North Sea, companies were awarded parallel preengineering contracts for preliminary design work leading to a full engineering contract for one of the companies in the summer.
Aker Engineering will compete with Kvaerner Engineering on design of four of five topside modules. The fifth module containing drilling facilities will be designed in parallel by Transocean Drilling (formerly Aker Drilling) and a joint venture of Smedvig IPR and Norwegian Rig Consultants. The four contracts are worth 90 million kroner ($15.5 million).
Conoco also soon will award parallel preengineering contracts for the TLP's concrete substructure to Norwegian Contractors and a joint venture of Kvaerner, the French group Doris, and Skanska, a Swedish civil engineering group.
The Norwegian government has decided to exercise the sliding scale option to raise the state's total share of the field to 75%. Statoil has 10% and the state has a direct 65% holding.
Conoco has 18.125%, Finland's Neste Oy 5%, Norsk Hydro 1.25%, and Det Norske Oljeselskap AS 0.625%.
DUTCH NORTH SEA PROJECT
Amoco's Dutch North Sea project calls for a central gas processing/condensate separation and stabilization platform bridge linked to Amoco's existing Rijn oil production complex in Block P/15. There will also be six remote operated satellite producing facilities, including two subsea completions.
Gas will be piped to the Rotterdam area through a 26.3 mile pipeline and gas liquids through the Rijn oil line.
Amoco awarded the engineering design contract to Protech International BY.
Reserves for the project are in Blocks P/15 a-b, P/15c, P/18a and P/18c. Shareholders in the blocks are Amoco, Dyas BV, Veba Oil Nederland BV, Pacific Enterprises Oil Co. (Netherlands), Enserch Netherlands Inc., Oranje-Nassau Energie BV, Oranje-Nassau Energie Participatie Mij, BV, Clyde Petroleum (North Sea) Ltd., DSM Energie BV, DSM Energie (Rijn) BV.
The plan is subject to approval by the Netherlands Ministry of Economic Affairs.
TARTAN SHUTDOWN
Personnel were later returned to the Tartan platform, although production of oil and gas remained shut-in at presstime last week.
Texaco said pressure in the gas export line to the Claymore field beyond the subsea safety valve was being reduced in preparation for installation of a replacement spool on the riser.
Tartan also processes oil and gas from Petronella and Highlander subsea satellites. Production through the platform in January averaged 29,764 b/d of crude, 3,840 b/d of NGL, and 12 MMcfd of gas.
Gas from Tartan is used for gas lift and power generation on Occidental Petroleum (Caledonia)'s Claymore field. Production from Claymore and the Scapa subsea satellite were reduced to 23,000 b/d from 90,000 b/d immediately after the incident.
Oxy later raised Claymore/Scapa production to 40,000 b/d but plans to keep it at that level until gas is again available from Tartan. The company will move up scheduled maintenance programs from later in the summer which would have required reduced production levels.
Meantime, BP Exploration has resumed production through the Forties pipeline system after a 2 week shutdown to allow tie-in of the new 36 in. crude export pipeline and installation of a new topside emergency shutdown valve on the Brae import riser.
Production is still through the original 32 in. line. BP said the new 36 in. line will be commissioned later this month once cleaning is complete and all the users of the system have achieved a steady production level.
FLARE STACK DESIGN
The 623 ft tall, three sided steel flare pylon, set in 262 ft of water will be fabricated by Aker Verdal, Norway.
It will have a 360 ft tall concrete substructure to be built by Norwegian Contractors, Stavanger.
Statoil said the concept offers a number of important advantages over a traditional steel unit. The structure can be floated into position and installed the same way as large concrete platforms, and the entire installation process can be completed without using a crane barge. Maintenance will also be simpler and cheaper than for a steel structure.
Statoil said it asked eight companies to offer a new concept for flare stacks. Five proposed all steel structures, Norwegian Contractors offered the concrete/steel hybrid, and two declined the invitation.
OSEBERG PIPELINE JOBS
Norsk Hydro let a contract valued at about $23.2 million to Allseas Marine Contractors SA, Switzerland, to engineer, construct, and install a 9.25 mile, 14 in. multiphase pipeline that will transfer unprocessed production from Oseberg Platform C to Oseberg central field facilities.
Norsk Hydro also let a contract worth about $3.25 million to Seanor Engineering AS, Norway, for a 14 in. emergency shutdown valve for the C Platform pipeline.
Allseas is to have the Oseberg line installed by yearend 1991. Seanor is to deliver the emergency shutdown valve in October for installation in fourth quarter 1991.
The field is scheduled to start up in 1992.
Oseberg partners are operator Norsk Hydro 13.75%, Statoil and Norwegian government 65.04%, Saga Petroleum AS 8.61%, Elf Aquitaine Norge AS 5.6%, Mobil Exploration Norway Inc. 4.2%, and Total CFP 2.8%.
Copyright 1991 Oil & Gas Journal. All Rights Reserved.