Ekofisk automatic GPS subsidence measurements

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · Sea Technology

OSTI ID:525821

Mes, M J ^[1]; Landau, H; Luttenberger, C ^[2]

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1. Phillips Petroleum Co., Tananger (Norway)
2. TerraSat GmbH, Hoehenkirchen-Sieghertsbrumm (Germany)

A fully automatic GPS satellite-based procedure for the reliable measurement of subsidence of several platforms in almost real time is described. Measurements are made continuously on platforms in the North Sea Ekofisk Field area. The procedure also yields rate measurements, which are also essential for confirming platform safety, planning of remedial work, and verification of subsidence models. GPS measurements are more attractive than seabed pressure-gauge-based platform subsidence measurements-they are much cheaper to install and maintain and not subject to gauge drift. GPS measurements were coupled to oceanographic quantities such as the platform deck clearance, which leads to less complex offshore survey procedures. Ekofisk is an oil and gas field in the southern portion of the Norwegian North Sea. Late in 1984, it was noticed that the Ekofisk platform decks were closer to the sea surface than when the platforms were installed-subsidence was the only logical explanation. After the subsidence phenomenon was recognized, an accurate measurement method was needed to measure progression of subsidence and the associated subsidence rate. One available system for which no further development was needed, was the NAVSTAR GPS-measurements started in March 1985.

• OSTI ID: 525821
• Journal Information: Sea Technology, Journal Name: Sea Technology Journal Issue: 10 Vol. 37; ISSN 0093-3651; ISSN SEATAD
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
GROUND SUBSIDENCE
LEVELS
MEASURING METHODS
NORTH SEA
OFFSHORE DRILLING
OFFSHORE PLATFORMS
OIL FIELDS
PETROLEUM DEPOSITS
SATELLITES