Hostname: page-component-cd9895bd7-jkksz Total loading time: 0 Render date: 2024-12-26T08:05:39.113Z Has data issue: false hasContentIssue false
  • English
  • Français

Diagenetic sequences and K/Ar dating in Jurassic sandstones, Central Viking Graben: effects on reservoir properties

Published online by Cambridge University Press:  09 July 2018

M. Thomas
M. Thomas*
Affiliation:
Centre de recherche Elf-Aquitaine, Avenue du Président Angot, 64000 Pau, France
Get access Rights & Permissions [Opens in a new window]

Abstract

The differences noticed in the porosity-permeability values and the clay mineralogy of the Brent and Statfjord reservoirs of two closely related wells from the Central Viking Graben appear to be due essentially to diagenesis. According to their type, nature and relationships, the diagenetic phases are organized into three distinct sequences, each induced by distinct hydrodynamic systems. These systems are related to three main episodes of the geological history of the reservoirs, which were: the compaction-lithilication phase, the Kimmerian to Lower Cretaceous emersive phase, and the hydrologic loading of the deep parts of the basins and/or fault panels. The late diagenetic sequence is expressed by quartz overgrowths, blocky kaolinite and illite authigenesis. With a probable ‘catalytic’ effect of temperature, this sequence is the most intensely developed and so greatly damages the porosity and permeability. In the oil-bearing reservoirs of Well 25/4-1, the stage of evolution of this third diagenetic sequence is not well advanced: illitization was rapidly stopped by the hydrocarbon charge so that permeabilities remained satisfactory (up to 500 mD). In the water-zone of Well 25/4-5, illitization is extensive and permeabilities considerably reduced (lower than 5 mD). K/Ar dating of authigenic illites provides evidence of a late Eocene phase (40–44 Ma) as the maximum age for the hydrocarbon entrapment in Well 25/4-1, whereas the last illite authigenesis from the water-zone of Well 25/4-5 gives an Oligocene phase (28 Ma in the Statfjord Formation). These data indicate that fluid circulation was effective until this time in the down-dip faulted panel of Well 25/4-5, and has therefore been responsible for the drastic permeability reduction.

Type
Research Article
Information
Clay Minerals , Volume 21 , Issue 4 , October 1986 , pp. 695 - 710
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1986

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Almon, W.R. & Davies, D.K. (1979) Regional diagenetic trends in the lower Cretaceous Muddy Sandstone, Powder River Basin. Pp. 379–400 in: Aspects of Diagenesis (Scholle, P. A. and Schluger, P. R., editors). SEPM Spec. Publ. 26.Google Scholar
Bjørlykke, K., Elverhoi, A. & Malm, O. (1979) Diagenesis in Mesozoïc sandstones from Spitzbergen and the North Sea―a comparison. Geol. Rundschau 68, 1152–1171.Google Scholar
Blackbourn, G.A. (1984) Diagenetic history and reservoir quality of a Brent sand sequence. Clay Miner. 19, 377–389.Google Scholar
Curtis, C.D. (1983) Geochemistry of porosity enhancement and reduction in elastic sediments. Pp. 113–125 in: Petroleum Geochemistry and Exploration of Europe (Brooks, J., editor). Geol. Soc. Spec. Publ. 17.Google Scholar
Esquevin, J., Giblin, P. & Thomas, M. (1982) 25/4-1 et 25/4-5―Etude de géochimie minerale des réservoirs jurassiques (Viking graben; offshore norvégien). SNEA(P) internal report. Google Scholar
Hajash, A. (1981) Regional diagenetic trends in the Lower Cretaceous Muddy Sandstone, Powder River Basin―discussion. J. Sed. Petr. 51, 679–681.CrossRefGoogle Scholar
Hancock, N.J. & Taylor, A.M. (1978) Clay mineral diagenesis and oil migration in the Middle Jurassic Brent Sand Formation. J. Geol. Soc. Lond. 135, 69–71.Google Scholar
Hurst, A. & Irwin, H. (1982) Geological modelling of clay diagenesis in sandstones. Clay Miner. 17, 5–22.Google Scholar
Irwin, H., Curtis, C.D. & Coleman, M.H. (1977) Isotopic evidence for source of diagenetic carbonates formed during burial of organic-rich sediments. Nature 269, 209–213.Google Scholar
Lacharpagne, J.C. & Thomas, M. (1985) Geological modelling of the diagenesis in the Jurassic sandstones of the North Sea Basin―Phase report no. 1: Applications to the 10th round (Norway offshore). SNEA(P) internal report. Google Scholar
Morgan, J.J. (1967) Applications and limitations of chemical thermodynamics in natural water systems. In: Equilibrium Concepts in Natural Water Systems (Adv. Chem. Ser. 67). Am. Chem. Soc., Washington DC, USA.Google Scholar
O'Neil, J.R., Clayton, R.N. & Mayeda, T.K. (1969) Oxygen isotope fractionation in divalent metal carbonates. J. Chem. Physics 51, 5547–5558.Google Scholar
Sommer, F. (1978) Diagenesis of Jurassic sandstones in the Viking Graben. J. Geol. Soc. Lond. 135, 63–67.Google Scholar