Mineralogy and palaeoenvironments: the Weald Basin (Early Cretaceous), Southeast England

Akinlotan, Oladapo O.

doi:10.1002/dep2.32

Cited by 13 publications

(6 citation statements)

References 51 publications

(105 reference statements)

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“…This validation, thereby, allows an accurate petrophysical analysis of reservoir sandstones with broad ranges of textural and topological characteristics. The findings contribute also to the current geological knowledge regarding non-marine sandstones of Lower Cretaceous age (e.g., Akinlotan, 2017;Li et al, 2016;Ferreira et al, 2016) and specifically regarding the studied stratigraphic unit.…”

Section: Introductionsupporting

confidence: 56%

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

Haruzi¹,

Katsman²,

Halisch³

et al. 2020

Preprint

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Abstract. This paper presents a detailed description and evaluation of a multi-methodological petrophysical approach for the comprehensive multiscale characterization of reservoir sandstones. The suggested methodology enables the identification of Darcy-scale permeability links to an extensive set of geometrical, textural and topological rock descriptors quantified at the pore scale. This approach is applied to the study of samples from three consecutive sandstone layers of Lower Cretaceous age in northern Israel. These layers differ in features observed at the outcrop, hand specimen, petrographic microscope and micro-CT scales. Specifically, laboratory porosity and permeability measurements of several centimetre-sized samples show low variability in the quartz arenite (top and bottom) layers but high variability in the quartz wacke (middle) layer. The magnitudes of this variability are also confirmed by representative volume sizes and by statistical anisotropy analyses conducted on micro-CT-imaged 3D pore geometries. Two scales of porosity variability are revealed by applying variogram analysis to the top layer: fluctuations at 150 μm are due to variability in the pore size, and those at 2 mm are due to the occurrence of high- and low-porosity bands occluded by iron oxide cementation. This millimetre-scale variability is found to control the laboratory-measured macroscopic rock permeability. Good agreement between the permeability upscaled from the pore-scale modelling and the estimates based on laboratory measurements is shown for the quartz arenite (top) layer. The proposed multi-methodological approach leads to an accurate petrophysical characterization of reservoir sandstones with broad ranges of textural, topological and mineralogical characteristics and is particularly applicable for describing anisotropy at various rock scales. The results of this study also contribute to the geological interpretation of the studied stratigraphic units.

show abstract

Section: Introductionsupporting

confidence: 56%

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

Haruzi¹,

Katsman²,

Halisch³

et al. 2020

Preprint

View full text Add to dashboard Cite

show abstract

“…The findings contribute also to the current geological knowledge regarding non-marine sandstones of Lower Cretaceous age (e.g. Akinlotan, 2016Akinlotan, , 2017Akinlotan, , 2018Li et al, 2016;Ferreira et al, 2016) and specifically regarding the studied stratigraphic unit.…”

Section: Introductionsupporting

confidence: 54%

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

et al. 2021

View full text Add to dashboard Cite

Abstract. This paper presents a detailed description and evaluation of a multi-methodological petrophysical approach for the comprehensive multi-scale characterization of reservoir sandstones. The suggested methodology enables the identification of links between Darcy-scale permeability and an extensive set of geometrical, textural and topological rock descriptors quantified at the pore scale. This approach is applied to the study of samples from three consecutive sandstone layers of Lower Cretaceous age in northern Israel. These layers differ in features observed at the outcrop, hand specimen, petrographic microscope and micro-CT scales. Specifically, laboratory porosity and permeability measurements of several centimetre-sized samples show low variability in the quartz arenite (top and bottom) layers but high variability in the quartz wacke (middle) layer. The magnitudes of this variability are also confirmed by representative volume sizes and by anisotropy evaluations conducted on micro-CT-imaged 3-D pore geometries. Two scales of directional porosity variability are revealed in quartz arenite sandstone of the top layer: the pore size scale of ∼0.1 mm in all directions and ∼3.5 mm scale related to the occurrence of high- and low-porosity horizontal bands occluded by Fe oxide cementation. This millimetre-scale variability controls the laboratory-measured macroscopic rock permeability. More heterogeneous pore structures were revealed in the quartz wacke sandstone of the intermediate layer, which shows high inverse correlation between porosity and clay matrix in the vertical direction attributed to depositional processes and comprises an internal spatial irregularity. Quartz arenite sandstone of the bottom layer is homogenous and isotropic in the investigated domain, revealing porosity variability at a ∼0.1 mm scale, which is associated with the average pore size. Good agreement between the permeability upscaled from the pore-scale modelling and the estimates based on laboratory measurements is shown for the quartz arenite layers. The proposed multi-methodological approach leads to an accurate petrophysical characterization of reservoir sandstones with broad ranges of textural, topological and mineralogical characteristics and is particularly applicable for describing anisotropy and heterogeneity of sandstones on various rock scales. The results of this study also contribute to the geological interpretation of the studied stratigraphic units.

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“…12% siderite and 26% kaolinite. The clay mineralogy of the facies within the Wadhurst Clay Formation has previously been discussed (Akinlotan, 2017 a ). Kaolinite in the host mudstone in this location is 23% (O. O. Akinlotan, unpub.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, the occurrence of these sideritic ironstones shows that diagenesis in the Wealden strata was limited to the early phase, which means that diagenetic alteration to the rocks was minimal. It is important to note that the clay minerals within the host rocks of the siderites have been described as detrital in origin (Jeans et al 2001; Jeans, 2006; Akinlotan, 2017 a ) and that any diagenetic alteration to them was negligible (Allen, 1981; Sladen & Batten, 1984; Akinlotan, 2017 a ). The relatively shallow depth of burial of the Wealden facies (Allen, 1981; Sladen & Batten, 1984) and the low geothermal gradient of ~10 °C km −1 (Rollin, 1995; Westaway, Maddy & Bridgland, 2002) meant that there was no significant diagenetic alteration to the Wealden facies pointing to an early phase of diagenesis.…”

Section: Discussionmentioning

confidence: 99%

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

Akinlotan

2017

Geol. Mag.

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The Lower Cretaceous Wealden sideritic ironstones have a wide occurrence and great potential to aid the reconstruction of the depositional environments of the Weald Basin in SE England. However, mineralogical and geochemical datasets on the ironstones are scarce in the literature. Geochemical and mineralogical data on the sideritic ironstones are presented from the Wadhurst Clay Formation within the Weald Basin. The mineralogy of the ironstones was examined using a PANalytical X'Pert Pro X-ray diffractometer and PANalytical's HighScore Plus software. Elemental composition of the ironstones was measured using a PANalytical MiniPal2 ED-XRF (benchtop X-ray spectrometer). The examination of the mineralogy of the Wealden ironstones confirms the presence of early diagenetic siderites. The trace-element assemblage shows that the sideritic ironstones are chemically pure pointing to a freshwater origin. The sideritic ironstones reveal anoxic conditions and palaeo-salinity in the basin. More generally, it is suggested that the composition of the host rocks has significant controls on the composition of sideritic ironstones in sedimentary basins. This work reinforces the importance of the composition of sideritic ironstones as useful non-traditional data for understanding the depositional settings of sedimentary basins, especially when traditional datasets are not readily available or insufficient.

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Mineralogy and palaeoenvironments: the Weald Basin (Early Cretaceous), Southeast England

Cited by 13 publications

References 51 publications

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

Benchmark study using a multi-scale, multi-methodological approach for the petrophysical characterization of reservoir sandstones

Sideritic ironstones as indicators of depositional environments in the Weald Basin (Early Cretaceous) SE England

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