The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben
A cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG) log could be used as an indicator of reservoir qu...
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Geological Survey of Denmark and Greenland
2003
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ftdoajarticles:oai:doaj.org/article:f129d01159464778813aebeb5de1ceb4 2023-05-15T16:30:37+02:00 The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben Fabricius, Ida L. Fazladic, Louise Dahlerup Steinholm, Armgaard Korsbech 2003-10-01T00:00:00Z https://doaj.org/article/f129d01159464778813aebeb5de1ceb4 EN eng Geological Survey of Denmark and Greenland http://www.geus.dk/publications/bull/nr1_p349-366.pdf https://doaj.org/toc/1604-8156 1604-8156 https://doaj.org/article/f129d01159464778813aebeb5de1ceb4 Geological Survey of Denmark and Greenland Bulletin, Vol 01, Pp 349-366 (2003) Danish Central Graben North Sea Middle Jurassic sandstone reservoir gamma-ray spectometry mineralogy geochemistry Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 article 2003 ftdoajarticles 2022-12-31T16:35:14Z A cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG) log could be used as an indicator of reservoir quality. Core intervals of quartz arenites and quartz wackes were selected. Although no linear relationship was found between clay content and potassium (K), thorium (Th), or uranium (U), the K content characterises three discrete lithofacies. Lithofacies I has a grain-supported texture, with a predominance of quartz grains; only minor fine-grained matrix is present. Sandstones of lithofacies I have a low K content and most of the K is hosted in feldspar. Porosity varies between 23% and 28% and permeability is in the range 200-2000 mD. Lithofacies II sandstones have a grain-supported texture, with a predominance of quartz grains; fine-grained matrix fills the intergranular volume. Sandstones of lithofacies II have an intermediate K content, with K-feldspar, mica, and illite as the main sources. Porosity varies between 11% and 17% and permeability is in the range 0.4-25 mD. Lithofacies III has a matrix-supported texture with quartz grains floating in a clay-rich matrix. Samples from lithofacies III have the highest K signal. Illite and illitised kaolinite are roughly equal in importance as sources of K. Porosity is up to 11% and permeability up to 0.5 mD. The Th and U content of all lithofacies is governed primarily by the presence of heavy minerals; no apparent general relationship between U and Total Organic Carbon (TOC) was found. Comparisons between the core measurements of K, Th, and U, and the SNG log disclosed a discrepancy between the calibrations of laboratory and borehole measurements. For U the discrepancy contains an erratic element, whereas the difference for K and Th can be eliminated by correction factors. Thus, the conclusions based on laboratory measurements appear to be applicable to the log data, and, ... Article in Journal/Newspaper Greenland Geological Survey of Denmark and Greenland Bulletin Directory of Open Access Journals: DOAJ Articles Greenland |
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Danish Central Graben North Sea Middle Jurassic sandstone reservoir gamma-ray spectometry mineralogy geochemistry Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 |
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Danish Central Graben North Sea Middle Jurassic sandstone reservoir gamma-ray spectometry mineralogy geochemistry Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 Fabricius, Ida L. Fazladic, Louise Dahlerup Steinholm, Armgaard Korsbech The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
topic_facet |
Danish Central Graben North Sea Middle Jurassic sandstone reservoir gamma-ray spectometry mineralogy geochemistry Geology QE1-996.5 Geophysics. Cosmic physics QC801-809 |
description |
A cored sandstone interval from the Middle Jurassic Harald Field of the Danish North Sea was chosen for an investigation of the mineralogical sources for the gamma-ray activity, and with the purpose of determining how the Spectral Natural Gamma (SNG) log could be used as an indicator of reservoir quality. Core intervals of quartz arenites and quartz wackes were selected. Although no linear relationship was found between clay content and potassium (K), thorium (Th), or uranium (U), the K content characterises three discrete lithofacies. Lithofacies I has a grain-supported texture, with a predominance of quartz grains; only minor fine-grained matrix is present. Sandstones of lithofacies I have a low K content and most of the K is hosted in feldspar. Porosity varies between 23% and 28% and permeability is in the range 200-2000 mD. Lithofacies II sandstones have a grain-supported texture, with a predominance of quartz grains; fine-grained matrix fills the intergranular volume. Sandstones of lithofacies II have an intermediate K content, with K-feldspar, mica, and illite as the main sources. Porosity varies between 11% and 17% and permeability is in the range 0.4-25 mD. Lithofacies III has a matrix-supported texture with quartz grains floating in a clay-rich matrix. Samples from lithofacies III have the highest K signal. Illite and illitised kaolinite are roughly equal in importance as sources of K. Porosity is up to 11% and permeability up to 0.5 mD. The Th and U content of all lithofacies is governed primarily by the presence of heavy minerals; no apparent general relationship between U and Total Organic Carbon (TOC) was found. Comparisons between the core measurements of K, Th, and U, and the SNG log disclosed a discrepancy between the calibrations of laboratory and borehole measurements. For U the discrepancy contains an erratic element, whereas the difference for K and Th can be eliminated by correction factors. Thus, the conclusions based on laboratory measurements appear to be applicable to the log data, and, ... |
format |
Article in Journal/Newspaper |
author |
Fabricius, Ida L. Fazladic, Louise Dahlerup Steinholm, Armgaard Korsbech |
author_facet |
Fabricius, Ida L. Fazladic, Louise Dahlerup Steinholm, Armgaard Korsbech |
author_sort |
Fabricius, Ida L. |
title |
The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
title_short |
The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
title_full |
The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
title_fullStr |
The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
title_full_unstemmed |
The Jurassic of Denmark and Greenland: The use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the Middle Jurassic of the Harald Field, Danish Central Graben |
title_sort |
jurassic of denmark and greenland: the use of spectral natural gamma-ray analysis in reservoir evaluation of siliciclastic sediments: a case study from the middle jurassic of the harald field, danish central graben |
publisher |
Geological Survey of Denmark and Greenland |
publishDate |
2003 |
url |
https://doaj.org/article/f129d01159464778813aebeb5de1ceb4 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Geological Survey of Denmark and Greenland Bulletin |
genre_facet |
Greenland Geological Survey of Denmark and Greenland Bulletin |
op_source |
Geological Survey of Denmark and Greenland Bulletin, Vol 01, Pp 349-366 (2003) |
op_relation |
http://www.geus.dk/publications/bull/nr1_p349-366.pdf https://doaj.org/toc/1604-8156 1604-8156 https://doaj.org/article/f129d01159464778813aebeb5de1ceb4 |
_version_ |
1766020347271839744 |