Grenland Group was awarded the contract to modify the Oseberg Field Centre to operate at a lower production pressure.
Oseberg LPP - Modification of the Oseberg Field Centre to operate at lower production pressure
In September 2007, Norsk Hydro awarded Grenland Group the contract to modify the Oseberg Field Centre to operate at a lower production pressure.
The contract value was NOK 625 million, and the project represented a major breakthrough for the company in the market of maintenance and modifications.
After 18 years of oil production and six years of gas exports from the Oseberg Field Centre, pressure in the Oseberg reservoirs had declined. By modifying the processing facility, StatoilHydro will be in a position to decrease the intake pressure for the oil coming up to the Centre.
Oil recovery may be increased by up to three to four million standard cubic metres, corresponding to 20–25 million barrels, by introducing low pressure production.
Oil and gas have always been taken in at first-phase separators on Oseberg A. The first-phase separators had a pressure of 67 bar, but the processing facility was now 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 had fallen by 70 to 100 bar.
Up to 10 wells were adapted into second phase separators. Start-up of low-pressure production was expected in the autumn of 2009, and the contract period ran right up to spring 2010, when the facility was to be completed.
The modification project was very extensive and complex, and involved work on two platforms. Grenland Group's project involved engineering, procurement, construction and installation.
The work consisted 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 the bridge to Oseberg A, where the pipes were connected to the Oseberg A second-phase separators.
In addition, Grenland Group upgraded the gas compressors and production trains in order to produce at low pressure.
