X-ray microtomography characterization of carbonate microbialites from a hypersaline coastal lagoon in the Rio de Janeiro State—Brazil

Machado, Alessandra Silveira; Bó, Patrick Francisco Führ Dal'; Lima, I.; Borghi, Leonardo; Lopes, Ricardo Tadeu

doi:10.1016/j.nima.2014.12.107

Cited by 15 publications

(10 citation statements)

References 7 publications

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“…Until now, lagoon sediments have not been largely studied with X-ray CT techniques. The applications include the examination of stromatolites from a hypersaline lagoon [10], the estimation of the bulk density of surface sediment in the lagoon of Venice for studies on sediment erosion [11], and the identification of sedimentary facies from the Pappas Lagoon in Greece [12]. In the present study, we explore various software algorithms for optimal observation of the structure of sediment cores prior to opening.…”

Section: Introductionmentioning

confidence: 99%

X-ray Computed Tomography as a Tool for Screening Sediment Cores: An Application to the Lagoons of the Po River Delta (Italy)

Zonta

Fontolan

Cassin

et al. 2021

JMSE

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Lagoon sediments have heterogeneous structure and texture, contain shells and plants and are often highly bioturbated and disturbed by human activities. In such sediments, the selection of representative cores and the choice of a subsampling strategy are important but difficult. In this study, we examine the usefulness of X-ray computed tomography (CT) for inferring sediment features that will help in making optimal decisions prior to core opening (24 cores from seven lagoons). Various algorithms (intensity projections, slice thickness, axial and sagittal images, CT number profiles and volumetric region of interest) are tested to visualise low- and high-density volumes or objects and to quantify the relations between the average volumetric CT number and the bulk density of the sediment matrix. The CT number is related mainly to water content and indirectly to total nitrogen and <16-μm grain-size fraction (model R2 = 0.94). The outliers are attributed to a weak correspondence between the fraction of sediment sampled for water content determination and the volume of sediment matrix used for CT number measurements in highly heterogeneous sediment slices. In conclusion, CT is a powerful tool for the initial screening of cores recovered from heterogeneous lagoon sediments. The adequate use of available algorithms may provide quantitative information on various sediment features, allowing the purposeful selection of cores and subsamples for further investigation.

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Section: Introductionmentioning

confidence: 99%

X-ray Computed Tomography as a Tool for Screening Sediment Cores: An Application to the Lagoons of the Po River Delta (Italy)

Zonta

Fontolan

Cassin

et al. 2021

JMSE

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“…The X‐ray microtomography (micro‐CT) is a three‐dimensional image processing technique that uses a series of bidimensional projections in constant angular steps to reconstruct an object using an appropriate mathematical algorithm. The micro‐CT yields two‐ and three‐ dimensional models that can provide technical features, such as internal structures, textures, characteristics of the mineralogy, quantify porosity, and others …”

Section: Introductionmentioning

confidence: 99%

Characterization of carbonate rocks through X‐ray microfluorescence and X‐ray computed microtomography

et al. 2019

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Carbonate rocks play an important role in petroleum geology by acting as reservoir rocks, generators, and even hydrocarbon sealants, accounting for about half of the oil and gas reserves known in the world. The study of these carbonate rocks have become very important in the hydrocarbon exploration scene in Brazil because of they consist in analogous for reservoir rocks of the presalt interval. Thus, the objective of this research was to use X‐ray microfluorescence (micro‐XRF) and X‐ray microtomography analysis, as complementary techniques, in order to characterize samples of carbonate rocks in respect to their structures, textures, mineralogy, and pores. The microtomographic analyses allowed the identification of the horizontal structures as parallel lamination, horizontal, and vertical fractures filled by calcite and biotic constituents (gastropods bioclasts). Different composition of minerals were also identified, as calcite, quartz, feldspars, iron sulfides, and oxides. The porosity (ranges <1 to17%), and the high‐density elements could also be quantified, as well as their distribution in each sample. The micro‐XRF analysis present a direct relationship with the distribution of minerals that compound carbonate rocks, highlighting some structures, as well as helping to identify trace and minor elements in the carbonates (Mn, Sr, and Mg).

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“…Youssef et al (2007) validated their 3D pore system models created from µCT data as a function of porosity and permeability estimates. Machado et al (2015) and Corbett et al (2015) used microbialite rocks, similar to the one used in this work, to characterize the mineralogy and porosity distribution of complex carbonate rocks. However, none of these studies analyzed the representativeness of the digital poroperm results.…”

Section: Introductionmentioning

confidence: 99%

Representative Elementary Volume of a Region of Interest of a Heterogeneous Carbonate Rock Using X-Ray Computed Microtomography and Numerical Simulation

Silva¹,

Rios²,

Hoerlle³

et al. 2018

Braz J Geophys

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ABSTRACT. Characterization of carbonate rocks presents several challenges regarding the acquisition of petrophysical parameters and the understanding of fluid-flow dynamics in their pore system. To face these challenges, techniques such as X-ray microtomography, three-dimensional digital model reconstruction and fluid-flow numerical simulations have been continuously developed and improved. This study analyzes the representative elementary volume (REV) of a region of interest (ROI) of a highly heterogeneous stromatolite sample. Porosity and permeability are estimated for different subvolumes of the sample based on digital petrophysics. All necessary steps for reconstruction and segmentation of the complex pore system of the sample, as well as numerical simulations of fluid flow, are presented and discussed. The workflow is promising for reservoir evaluation because it can be applied to any type of carbonate rock.Keywords: Stromatolite, mCT, segmentation, REV, digital petrophysicsRESUMO. A caracterização de rochas carbonáticas apresenta diversos desafios quanto à determinação de seus parâmetros petrofísicos e o entendimento da dinâmica de escoamento de fluidos em seus sistemas porosos. Técnicas como a microtomografia de raios X, a modelagem digital tridimensional e a simulação numérica do escoamento de fluidos têm sido continuamente desenvolvidas e aprimoradas para superar esses desafios. Este estudo analisa o volume elementar representativo (REV) em uma região de interesse (ROI) de uma amostra de estromatólito altamente heterogênea. A porosidade e a permeabilidade são estimadas em diferentes subvolumes da amostra através da petrofísica digital. São apresentadas e discutidas todas as etapas necessárias para a reconstrução e segmentação do sistema poroso e a simulação numérica do escoamento de fluidos. A metodologia é promissora para avalição de reservatórios visto que o fluxo de trabalho pode ser aplicado a qualquer tipo de rocha carbonática.Palavras-chave: Estromatólitos, mCT, segmentação, REV, petrofísica digital

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X-ray microtomography characterization of carbonate microbialites from a hypersaline coastal lagoon in the Rio de Janeiro State—Brazil

Cited by 15 publications

References 7 publications

X-ray Computed Tomography as a Tool for Screening Sediment Cores: An Application to the Lagoons of the Po River Delta (Italy)

X-ray Computed Tomography as a Tool for Screening Sediment Cores: An Application to the Lagoons of the Po River Delta (Italy)

Characterization of carbonate rocks through X‐ray microfluorescence and X‐ray computed microtomography

Representative Elementary Volume of a Region of Interest of a Heterogeneous Carbonate Rock Using X-Ray Computed Microtomography and Numerical Simulation

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