Relationship between diagenesis, porosity reduction, and oil emplacement in late Carboniferous sandstone reservoirs, Bothamsall Oilfield, E Midlands

Hawkins, P. J.

doi:10.1144/gsjgs.135.1.0007

Cited by 71 publications

(18 citation statements)

References 14 publications

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“…These have been interpreted as representing delta-front and low-sinuousity fluviatile deposits (Hawkins 1972, Guion 1971.…”

Section: Petrographymentioning

confidence: 99%

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

Warren

1987

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Within the fluviatile reservoir sandstones of the Bothamsall oilfield, authigenic cements of early quartz, kaolinite and illite predominate. Detrital feldspars show varying degrees of alteration and muscovite micas are commonly altered to intergrowths of kaolinite and illite.Solution-mineral equilibria in the idealized system of K20-A1203-SiO2-H20 are used to relate the simple silicate mineral assemblage observed to possible pore-fluid compositions. Previous studies considered aluminium to be immobile in this system. Petrographic evidence of the paragenetic sequence at Bothamsall indicates that aluminium is mobile, albeit over short distances. This study therefore considers aluminium mobility in the solution-mineral equilibria. Graphical plots of total aluminium versus pH for given potassium ion activity, at a temperature of 298 K, are constructed to illustrate the stability fields of the phases identified. These show that aluminium can be an important component, together with pH and potassium-ion activity, in affecting mineral stabilities in this system.The existence of several co-stable phases at Bothamsall considerably reduces the possible permutations for pore-fluid chemistry; kaolinite-illite alteration of mica proves particularly sensitive in this respect. The relative merits of two different pore-fluid models are compared: one, where the pore-fluid composition is considered to be constant in an open system, and another where the pore-fluid composition is assumed to vary in response to in situ mineralogy in a closed system. The former would require a very restricted range of pore-fluid compositions to result in the diagenetic modifications observed, whereas a wide range of pore fluids could evolve in a closed system driven by feldspar dissolution. This pore-fluid evolutionary model is preferred.

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“…These have been interpreted as representing delta-front and low-sinuousity fluviatile deposits (Hawkins 1972, Guion 1971.…”

Section: Petrographymentioning

confidence: 99%

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

Warren

1987

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“…It postdates at least some quartz cement and predates the ferroan dolomite. It may be a late cement as in the nearby Bothamsall oil field (Hawkins, 1972(Hawkins, , 1978.…”

Section: Late Diagenesismentioning

confidence: 99%

Controls on mineral authigenesis in Coal Measures sandstones of the East Midlands, UK

Huggett

1984

Clay miner.

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Authigenic clay mineral formation in fluvial sandstones and one brackish sandstone from the lower and middle Coal Measures of the East Midlands has been studied using XRD, optical microscopy and a variety of electron optical techniques. The sandstones are quartz-rich with minor feldspar and mica. The clay minerals present are kaolinite, chlorite and illite; they form 10-15% by volume of most of the sandstones. Both detrital and authigenic illite and chlorite are present but the kaolinite is entirely authigenic. Kaolinite and illite authigenesis has been important in all the sandstones but authigenic chlorite is only abundant in the phyllosilicate-rich Silkstone sandstone. The controlling factors in the diagenesis of the sandstones were primary composition, environment of deposition, bed thickness, pore-fluid migration and composition, pressure and temperature. These interacting factors have been of varying importance in time and space in the diagenesis of the sandstones. Authigenic clay morphology appears to have been controlled by time and environment of formation, pore fluid chemistry and, possibly, parent minerals.In the East Midlands the Westphalian Coal Measures consist of fluvial channel sands, channel abandonment silts, interdistributory silts, shales and coals, with occasional marine bands. In order to investigate the environmental and physico-chemical controls on mineral authigenesis in the Coal Measures sandstones, in particular the clay mineral authigenesis, core samples were obtained from five wells near Gainsborough in Lincolnshire (Fig. I). The wells straddle the gentle WSW-ENE-trending Walkeringham anticline. Ten fluvial sandstones were extensively sampled, of which the present paper is concerned chiefly with the five shown in Fig. 1. One brackish-water sandstone, the Silkstone (Fig. 1), was also sampled; it is known to be brackish from the presence of the Estheria band within the sandstone (Calver, 1968). Eight interfluvial and channel abandonment siltstone facies were sampled; only one sample of each siltstone was taken. TECHNIQUESThe observations presented here were made using a light-optical microscope, a Jeol JSM 35 scanning electron microscope (SEM) with energy-dispersive X-ray analysis (EDAX) and cathodoluminescence analysis facilities, an AEI high-voltage electron microscope (HVEM), a Jeol 120 CX scanning transmission electron microscope (STEM) with EDAX, and a Jeol superprobe JXA 733 with wavelength-dispersive X-ray analysis which was used for backscattered electron imaging (BEI). All minerals named in the Figures were 9 1984 The Mineralogical Society

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“…The presence and growth of illite on kaolinite indicates its later origin than kaolinite. During diagenesis sediments were subjected to different conditions which might activate sources of silica for quartz cementation, such as dissolution of feldspar (Hawkins, 1978), pressure solution (Bjørlykke et al, 1986;Houseknecht, 1988;Dutton and Diggs, 1990;Bjørlykke and Egeberg, 1993;Dutton, 1993;Walderhaug, 1994), replacement of quartz and feldspar by calcite (Burley and Kantorowicz, 1986) and transformation of clay (Hower et al, 1976;Boles and Franks, 1979). For every mole of K-feldspar altered to kaolinite, two moles of silica are released and made available for cement (Siever, 1957).…”

Section: Paragenetic Sequencementioning

confidence: 99%

The effects of diagenesis on the reservoir characters in sandstones of the Late Cretaceous Pab Formation, Kirthar Fold Belt, southern Pakistan

Umar

Friis

Khan

et al. 2011

Journal of Asian Earth Sciences

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Relationship between diagenesis, porosity reduction, and oil emplacement in late Carboniferous sandstone reservoirs, Bothamsall Oilfield, E Midlands

Cited by 71 publications

References 14 publications

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

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

Controls on mineral authigenesis in Coal Measures sandstones of the East Midlands, UK

The effects of diagenesis on the reservoir characters in sandstones of the Late Cretaceous Pab Formation, Kirthar Fold Belt, southern Pakistan

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