Lyell Collection
Journal of the Geological Society
Lyell Centre  |   Lyell Collection  |   Subscriptions   |   Geological Society  |   Email alerts  |   Online bookshop  |   Help

Keywords:
Author:
Advanced search>>
This Article
Right arrow Full Text (PDF)
Right arrow References
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Selley, R. C.
Right arrow Search for Related Content
GeoRef
Right arrow GeoRef Citation
Journal of the Geological Society; 1978; v. 135; issue.1; p. 119-132;
DOI: 10.1144/gsjgs.135.1.0119
© 1978 Geological Society of London

Porosity gradients in North Sea oil-bearing sandstones

R. C. Selley

The relationship between porosity and burial depth of sandstone reservoirs is complex. It depends on primary porosity, which is related to grain-size and depositional process and also on the porosity gradient (the change in porosity with depth) which, in most cases, is linear.

This relationship may be expressed as: {varphi}d ={varphi}p – G.D, where {varphi}d is the porosity at depth D below surface, {varphi}p is the primary depositional porosity, and G is the porosity gradient in % porosity per 1000 ft (305 m). Porosity gradients decrease with increasing quartz content, abnormal pressures, and in the presence of hydrocarbons. They increase with increasing geothermal gradient. There are at present insufficient data to quantify these relationships.

Empirically derived porosity gradients for North Sea Rotliegendes, Jurassic and Palaeocene reservoir sandstones are 2.2, 2.6 and 2.9 per cent per 1000 ft (305 m) respectively.

When calibrated with the porosity spectra of the various facies, graphs can be drawn showing the depth: porosity windows within which economic reservoirs may be found.




This article has been cited by other articles:


Home page
 Bulletin of Canadian Petroleum GeologyHome page
R. G. Harris, R. G. Harris, and R. M. Bustin
Diagenesis, reservoir quality, and production trends of Doig Formation sand bodies in the Peace River area of Western Canada
Bulletin of Canadian Petroleum Geology, 2000; 48: 339 - 359.
[Abstract] [Full Text] [PDF]

Home page
 Clay MineralsHome page
D. M. CONYBEARE and H. F. SHAW
Fracturing, overpressure release and carbonate cementation in the Everest Complex, North Sea
Clay Minerals, 2000; 35: 135 - 149.
[Abstract] [Full Text] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
C. Y. McCants and S. D. Burley
Reservoir architecture and diagenesis in downthrown fault block plays: the Lowlander Prospect of Block 14/20b, Witch Ground Graben, Outer Moray Firth, UK North Sea
Geological Society, London, Special Publications, 1996; 114: 251 - 285.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
K. Bjorlykke, T. Nedkvitne, M. Ramm, and G. C. Saigal
Diagenetic processes in the Brent Group (Middle Jurassic) reservoirs of the North Sea: an overview
Geological Society, London, Special Publications, 1992; 61: 263 - 287.
[Abstract] [PDF]

Home page
 Geological Society, London, Special PublicationsHome page
S. N. Palmer and M. E. Barton
Porosity reduction, microfabric and resultant lithification in UK uncemented sands
Geological Society, London, Special Publications, 1987; 36: 29 - 40.
[Abstract] [PDF]

Home page
 Journal of the Geological SocietyHome page
J. Watson
Northern Scotland as an Atlantic-North Sea divide
Journal of the Geological Society, 1985; 142: 221 - 243.
[Abstract] [PDF]

Home page
 Journal of the Geological SocietyHome page
E. H. Rutter
Pressure solution in nature, theory and experiment
Journal of the Geological Society, 1983; 140: 725 - 740.
[Abstract] [PDF]