Reservoir aspects of Ekofisk subsidence

Journal Article · Sat Jul 01 04:00:00 EDT 1989 · Journal of Petroleum Technology; (USA)

DOI:https://doi.org/10.2118/17852-PA· OSTI ID:5627180

Sulak, R M; Danielsen, J ^[1]

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1. Phillips Petroleum Co. (NO)

In Nov. 1984, Phillips Petroleum Co. discovered subsidence of the seabed overlying the Ekofisk oil reservoirs offshore Norway. This phenomenon is the result of the compaction of the porous chalk reservoirs and the transmission of this compaction through the overburden to the seafloor. This paper describes the geolgoic- and reservoir-related aspects of subsidence, including the mechanism leading to reservoir compaction and its effect on reservoir performance. The compaction of the Ekofisk reservoirs is shown to be a result of pore-pressure depletion. Although some of the compaction is elastic, the bulk results from plastic deformation (pore collapse) of high-porosity chalk. Reservoir compaction is shown to cause subsidence of the seabed through deformation of the overlying sediments. Reservoir compaction has also had a pressure-maintenance effect on the reservoir. Thus far, no loss in reservoir productivity has been observed. On the basis of analogy with the neighboring West Ekofisk field, no loss in reservoir productivity is anticipated, at least for the near future.

• OSTI ID: 5627180
• Journal Information: Journal of Petroleum Technology; (USA), Journal Name: Journal of Petroleum Technology; (USA) Vol. 41:7; ISSN JPTJA; ISSN 0022-3522
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
42 ENGINEERING
423000 -- Engineering-- Marine Engineering-- (1980-)
DATA PROCESSING
DEFORMATION
EUROPE
GEOLOGIC DEPOSITS
GEOPHYSICAL SURVEYS
GROUND SUBSIDENCE
MAINTENANCE
MINERAL RESOURCES
NORWAY
OFFSHORE OPERATIONS
OIL FIELDS
PERFORMANCE TESTING
PETROLEUM DEPOSITS
POROSITY
PROCESSING
PRODUCTIVITY
RESERVOIR PRESSURE
RESOURCES
SCANDINAVIA
SEISMIC SURVEYS
SURVEYS
TECHNOLOGY ASSESSMENT
TESTING
WESTERN EUROPE