Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Petroleum Geoscience

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nordgård Bolås, H. M. Articles by Hermanrud, C. Search for Related Content GeoRef GeoRef Citation

Hydrocarbon leakage processes and trap retention capacities offshore Norway

Statoil ASA, Research Centre, N-7005Trondheim, Norway (e-mail: hnb@statoil.com; che@statoil.com)

Associations between high overpressures and sparse hydrocarbon occurrence are commonly ascribed to hydrocarbon leakage through pressure-induced fractures in the cap rock. However, several hydrocarbon traps in the North Viking Graben area in the North Sea still contain abundant commercial volumes of hydrocarbons at very high pore pressures. By contrast, a majority of the overpressured structures at the Halten Terrace further to the north have leaked hydrocarbons, even at considerably lower overpressures.

A selection of wells in the North Viking Graben and the Halten Terrace areas was investigated to find possible explanations for these observations. Distinct regional differences emerged, as the emptied reservoirs at the Halten Terrace generally have higher retention capacities than the overpressured discoveries in the North Viking Graben area. Thus, there appears to be a lack of any clear relationship between structures emptied of hydrocarbons and low retention capacities, which could be expected if pressure-induced fracturing of the cap rock was the main process of the hydrocarbon leakage.

The regional differences in retention capacities were mainly attributed to different leakage processes in the two basins. Stress history variations are suggested to be the main controlling factor of these leakage processes.

KEYWORDS: oil and gas entrapment, high pressure, stress, seal, fracture

This article has been cited by other articles:

				P. H. NADEAU, P. A. BJORKUM, and O. WALDERHAUG Petroleum system analysis: impact of shale diagenesis on reservoir fluid pressure, hydrocarbon migration, and biodegradation risks Geological Society, London, Petroleum Geology Conference series, January 1, 2005; 6(0): 1267 - 1274. [Abstract] [PDF]