Microcrystalline Quartz Generation and the Preservation of Porosity In Sandstones: Evidence from the Upper Cretaceous of the Subhercynian Basin, Germany

French, Marsha W.; Worden, Richard H.; Mariani, Elisabetta; Larese, Richard E.; Mueller, R.R.; Kliewer, Chris E.

doi:10.2110/jsr.2012.39

Cited by 42 publications

(23 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Microquartz coatings have been described as a layer of random oriented, micro-sized quartz crystals crystallographiclly misoriented with respect to the host grain (e.g. French et al, 2012;French and Worden, 2013). Microquartz can be observed in several appearances in the Skagerrak sandstones, such as a coating layer below clay coatings (Fig 7C & E) or as single crystals, outgrowing clay mineral coatings (Fig.…”

Section: Microquartz Grain Coatingsmentioning

confidence: 99%

“…There are many studies where deep reservoir porosity is linked to early diagenetic clay or microquartz grain coats (e.g. Pittman et al, 1992;Ehrenberg, 1993;Aase et al, 1996;Bloch et al, 2002;Ajdukiewicz and Lander, 2010;Ajdukiewicz and Larese, 2012;French et al, 2012;Worden et al, 2012). These studies have shown that quartz-rich sandstones with well-developed and continuous diagenetic clay or microquartz grain coats contain a much lower volume of macro-quartz cement than without such coatings (Ajdukiewicz and Lander, 2010).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Exceptional reservoir quality in HPHT reservoir settings: Examples from the Skagerrak Formation of the Heron Cluster, North Sea, UK

Stricker

Jones

Sathar

et al. 2016

Marine and Petroleum Geology

View full text Add to dashboard Cite

(2016) 'Exceptional reservoir quality in HPHT reservoir settings : examples from the Skagerrak Formation of the Heron Cluster, UK, North Sea.', Marine and petroleum geology., 77 . pp. 198-215. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. cementation and has had little to no effect on porosity preservation. The formation of welldeveloped authigenic chlorite (>70% surface coating) and, to a lesser extent illite clay coats with burial had a positive effect on porosity preservation even though permeability was marginally reduced in the illite-rich sandstones. A schematic porosity and quartz cement evolution model has been developed which allows for pre-drill prediction of reservoir quality in the Heron Cluster and provide valuable insights for other complex high-pressure hightemperature reservoirs.

show abstract

Section: Microquartz Grain Coatingsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exceptional reservoir quality in HPHT reservoir settings: Examples from the Skagerrak Formation of the Heron Cluster, North Sea, UK

Stricker

Jones

Sathar

et al. 2016

Marine and Petroleum Geology

View full text Add to dashboard Cite

show abstract

“…Current understanding of porosity preservation in deeply buried sandstone reservoirs (.4000 mbsf, metres below sea floor) tends to be focused on how coatings of clay and microquartz on detrital grains can inhibit macroquartz cementation. There are many studies where deep reservoir porosity is linked to early diagenetic clay or microquartz grain coats (Pittman et al 1992;Ehrenberg 1993;Aase et al 1996;Bloch et al 2002;Berger et al 2009;Ajdukiewicz & Lander 2010;Ajdukiewicz & Larese 2012;French et al 2012;Worden et al 2012;Bahlis & De Ros 2013). These studies have proven that quartz-rich sandstones with robust and continuous diagenetic clay or microquartz grain coats contain a much lower volume of macroquartz cement than expected (Berger et al 2009;Ajdukiewicz & Lander 2010).…”

mentioning

confidence: 99%

Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Stricker¹,

Jones²

2016

View full text Add to dashboard Cite

Current understanding of porosity preservation in deeply buried sandstone reservoirs tends to be focused on how diagenetic grain coatings of clay minerals and microquartz can inhibit macroquartz cementation. However, the importance of overpressure developed during initial (shallow) burial in maintaining high primary porosity during subsequent burial has generally not been appreciated. Where pore fluid pressures are high, and the vertical effective stress is low, the shallow arrest of compaction can allow preservation of high porosity and permeability at depths normally considered uneconomic. The deeply buried fluvial sandstone reservoirs of the Triassic Skagerrak Formation in the Central Graben, North Sea, show anomalously high porosities at depths greater than 3500 metres below sea floor (mbsf). Pore pressures can exceed 80 MPa in the upper part of the Skagerrak Formation at depths of 4000-5000 mbsf, where temperatures are above 1408C. The Skagerrak reservoirs commonly have high primary porosities of up to 35%, little macroquartz cement and variable amounts of diagenetic chlorite grain coats. This research sheds light on the complex controls on reservoir quality in the fluvial sandstones of the Skagerrak Formation by identifying the role of shallow overpressure in arresting mechanical compaction and the importance of chlorite detrital grain coatings in inhibiting macroquartz cement overgrowth as temperature increases during progressive burial.Gold Open Access: This article is published under the terms of the CC-BY 3.0 license.

show abstract

“…2001; Moxon & Rios 2004). The silica polymorphs in agates are similar in type and sequence to those in silcretes and have also been identified in the genesis of microcrystalline quartz in petroleum sandstone reservoirs (French et al. 2012; Worden et al.…”

Section: Introductionmentioning

confidence: 87%

Electron backscatter diffraction investigation of length‐fast chalcedony in agate: implications for agate genesis and growth mechanisms

French¹,

Worden²,

Lee³

2012

Geofluids

Self Cite

View full text Add to dashboard Cite

Agates of volcanic origin contain a range of silica minerals, with chalcedony and quartz arranged in concentric bands. Although agates are abundant worldwide, little is known about the genesis of their characteristic banding patterns. Current hypotheses suggest the bands result either from precipitation from convecting siliceous hydrothermal influxes or by in situ crystallization of a silica gel. This study combines the use of a variety of analytical techniques, including electron backscatter diffraction (EBSD), cathodoluminescence (CL), and Fourier transform infrared (FT-IR) spectroscopy, to characterize the silica minerals present and investigate their spatial and crystallographic relationships in the banding arrangement. Microstructural and spectroscopic observations reveal that chalcedony bands are composed of amorphous silica that also contains nanocrystalline and later-formed microcrystalline quartz. Nano-and microcrystalline quartz grew with a-axes perpendicular to the growth substrate, typical of length-fast chalcedony. The bands formed as a result of discrete influxes of silica-rich fluid. Within these individual bands, there is a sequence of minerals: chalcedony-A (with amorphous silica and nanocrystalline quartz) fi chalcedony-MQ (with microcrystalline quartz) fi quartz. This sequence is reflected in the degree of crystallinity, crystal orientations and water content and is analogous to a diagenetic cycle; the initial chalcedony portion of the band commences with amorphous silica with nanocrystalline quartz followed by fibrous microcrystalline quartz crystals; chalcedony then grades into larger equiaxial mesoquartz crystals. This paragenetic sequence suggests a viable model for the growth of chalcedony in agates.

show abstract

Microcrystalline Quartz Generation and the Preservation of Porosity In Sandstones: Evidence from the Upper Cretaceous of the Subhercynian Basin, Germany

Cited by 42 publications

References 30 publications

Exceptional reservoir quality in HPHT reservoir settings: Examples from the Skagerrak Formation of the Heron Cluster, North Sea, UK

Exceptional reservoir quality in HPHT reservoir settings: Examples from the Skagerrak Formation of the Heron Cluster, North Sea, UK

Enhanced porosity preservation by pore fluid overpressure and chlorite grain coatings in the Triassic Skagerrak, Central Graben, North Sea, UK

Electron backscatter diffraction investigation of length‐fast chalcedony in agate: implications for agate genesis and growth mechanisms

Contact Info

Product

Resources

About