The application of a solution-mineral equilibrium model to the diagenesis of Carboniferous sandstones, Bothamsall oilfield, East Midlands, England

Warren, Edward

doi:10.1144/gsl.sp.1987.036.01.06

Cited by 6 publications

(6 citation statements)

References 9 publications

(8 reference statements)

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“…These observations are identical to those described as expanded mica textures' in diagenetically modified sandstones (e.g. Bjùrlykke et al, 1979;Irwin & Hurst, 1983;Burley, 1984;Huggett, 1984Huggett, , 1986Kantorowicz, 1984;Bjùrlykke & Brendstal, 1986;Warren, 1987;Crowley, 1991) and weathered granites (e.g. Gilkes & Sudhiprakarn, 1979;Robertson & Eggleton, 1991).…”

Section: Petrography Of the Kaolinized Granitessupporting

confidence: 83%

Geological controls on kaolin particle shape and consequences for mineral processing

Psyrillos

Howe²,

Manning

et al. 1999

Clay miner.

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The kaolinized granites of St. Austell, England, are worked to produce a range of china clay products, for some of which the kaolin has to meet stringent particle shape and size specifications. Systematic petrographic study indicates that kaolin occurs in the form of two textural types: (i) finely crystalline kaolin (typically <5 µm in average diameter), which infills dissolution porosity of granitic feldspars, and (ii) coarsely crystalline vermiform aggregates (up to 100 µm or more in length), which are closely associated with expanded micas. The vermiform aggregates are characterized by an intergrowth of mica and kaolin crystals, which can be observed at scales of resolution offered by TEM. Textural and chemical evidence suggest that the expanded mica texture is probably the result of preferential precipitation of kaolin along mica cleavage planes and is not simply a process of chemical replacement.Petrographic examination of kaolin slurries sampled at different points in a typical refinery circuit indicates that platy products with high aspect ratio are derived exclusively from raw materials rich in vermiform aggregates. The fine scale intergrowth of kaolin and mica within the aggregates results in circumstances where mica persists through to fine grained products. Furthermore, the absence of Fe or other chemical components in the kaolin structure suggests that any iron reported for the final products may be a consequence of the presence of Fe-bearing mica within a very fine grained intergrowth.

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Section: Petrography Of the Kaolinized Granitessupporting

confidence: 83%

Geological controls on kaolin particle shape and consequences for mineral processing

Psyrillos

Howe²,

Manning

et al. 1999

Clay miner.

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“…Low potassium pore fluids in sublithic to subarkosic sandstones similar to those in the Rotliegendes are commonly formed during diagenesis as a result of dissolution of potassium bearing detrital phases like K-feldspar (e.g. see Warren 1987;Warren & Curtis 1989). To form potassium-rich pore fluids in these same sandstones, an external potassium-rich source, such as potassium salts, would be required.…”

Section: Controls On Reservoir Quality Variationsmentioning

confidence: 99%

Diagenetic controls on reservoir quality in Permian Rotliegendes sandstones, Jupiter Fields area, southern North Sea

Leveille

Primmer

Dudley

et al. 1997

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Reservoir quality in Lower Permian Rotliegendes Group sandstones in the Jupiter Fields varies considerably between fault blocks due to differing degrees of diagenetic alteration. Average porosities in individual fault blocks range from 12 to 21%, and geometric mean permeabilities vary between 2 and 200 md. Rotliegendes stratigraphy and sedimentology varies little across the area, and therefore does not strongly influence reservoir quality.The two most important diagenetic processes were the formation of authigenic illite and burial compaction. Illite growth mainly occurred during the Middle Jurassic to Early Cretaceous, coincident with maximum burial of the Rotliegendes. Fault blocks with good reservoir quality generally contain (1) relatively low illite abundances, (2) low-potassium illite, (3) increasing illite abundances with depth, (4) illite ages that decrease with depth and (5) comparatively low amounts of burial compaction. Fault blocks with poor reservoir quality all exhibit (1) high illite abundances, (2) high-potassium illite, (3) no consistent trend in illite abundances or age with depth and (4) high amounts of burial compaction. These observations are believed to indicate that reservoir quality was preferentially preserved in fault blocks that were structurally high during the main phase of illite growth. Factors contributing to the preservation of reservoir quality in structurally high fault blocks included differences in pore fluid chemistry, less burial compaction, and, in places, early hydrocarbon charging. Reservoir quality in undrilled fault blocks can be predicted by reconstructing the structural geometries present during the Mid-Jurassic to Early Cretaceous.

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“…Simultaneous formation of kaolinite and K-feldspar by muscovite breakdown in a closed system (< 50~ was discussed on a thermodynamic basis by Bjorkum and Gjelsvik (1988) for Jurassic North Sea sandstones. Mica alteration to clay and other minerals has been described for several sandstone sequences from different parts of the North Sea and other basins of the worlds (see, e.g., Burley, 1984;Huggett, 1984;Morad, 1986a;Boles, 1987;Warren, 1987).…”

Section: Introductionmentioning

confidence: 99%

Mica Alteration Reactions in Jurassic Reservoir Sandstones from the Haltenbanken Area, Offshore Norway

Morad

1990

Clays and clay miner.

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Abstract--Petrographic observations indicate that dolomite, siderite, pyrite, Ti oxides, quartz, and K-feldspar formed as by-products of mica alteration during diagenesis of Jurassic reservoir sandstones of the Haltenbanken area (offshore central Norway). These minerals precipitated on a mica-grain scale or a thin-section scale. Modal analyses and mass-balance calculations of muscovite alteration to kaolinite and of biotite to kaolinite, illite, and chlorite suggest limited elemental mobility during sandstone diagenesis. The alteration of mica to kaolinite occurred in sandstones buried <2200 m deep (present temperature < 70"C), whereas illitization and ehloritization of biotite occurred during burial to depths > 3000 m (present temperature >95~

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The application of a solution-mineral equilibrium model to the diagenesis of Carboniferous sandstones, Bothamsall oilfield, East Midlands, England

Cited by 6 publications

References 9 publications

Geological controls on kaolin particle shape and consequences for mineral processing

Geological controls on kaolin particle shape and consequences for mineral processing

Diagenetic controls on reservoir quality in Permian Rotliegendes sandstones, Jupiter Fields area, southern North Sea

Mica Alteration Reactions in Jurassic Reservoir Sandstones from the Haltenbanken Area, Offshore Norway

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