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Contract to Grenland Group for modifications on Oseberg

September 18, 2007, 10:30 CEST

The modifications will enable the production of more oil from wells with low reservoir pressure.


IMPORTANT: The successful Oseberg development in the North Sea was considered the single most important achievement for Hydro when it entered the oil business a few decades ago. Record high oil recovery has been possible through the innovative drilling of a vast number of long wells. 

After 18 years of oil production, and six years of gas exports from the Oseberg Field Centre, pressure in the Oseberg reservoirs has declined. By modifying the processing facility Hydro will be in a position to decrease the intake pressure for the oil coming up to the Centre.

Increasing production

 "We reckon on being able to increase oil recovery by up to 3-4 million standard cubic meters, or approximately 20-25 million barrels, by introducing low-pressure production," says head of Operations, Øystein Michelsen. He emphasizes that it is important to pump up as much oil as possible before increased gas exports further decrease reservoir pressure.

Oil and gas have always been taken in at first-phase separators on Oseberg B. The first-phase separators currently have a pressure of 67 bar, but the processing facility will now be modified so that the oil can go right into the second-phase separators, where the pressure is lower, at 20 bar. Since production on the Oseberg Field Centre started in December 1988, reservoir pressure has fallen by 70 bar to 100 bar.

Up to 10 wells adapted

Up to 10 wells will be adapted into second phase separators. Start-up of low-pressure production is expected in the autumn of 2009, and the contract period will run right up to spring 2010, when the facility will be completed.

The modification project is very extensive and complex, and involves work on two platforms. The contract with the Grenland Group involves engineering, procurement, construction and installation.

The work consists of installing low-pressure flow pipes and new low-pressure manifolds on Oseberg B, as well as the installation of pipes from the low-pressure manifolds on Oseberg B over bridge to Oseberg A, where the pipes will be connected to the Oseberg A second- phase separators.

In addition, the Grenland Group will upgrade the gas compressors and production trains in order to produce at low pressure.