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Francois Roure - One of the best experts on this subject based on the ideXlab platform.
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host rock dolomitization and Secondary Porosity development in the upper devonian cairn formation of the fairholme carbonate complex south west alberta canadian rockies diagenesis and geochemical modelling
Sedimentology, 2009Co-Authors: Veerle Vandeginste, Rudy Swennen, Mark H Reed, R M Ellam, Kirk G Osadetz, Francois RoureAbstract:The Upper Devonian carbonate reefs in West-central Alberta are important petroleum reservoirs that are well-known for their extensive Secondary Porosity. An outcrop analogue study indicates that an early matrix-selective dolomitization event occurred which is characterized by a major Late Devonian sea water component with increased salinity because of evaporation. It is interpreted that the matrix (replacive) dolomite formed during the Famennian as the result of a combination of both seepage and latent reflux dolomitization, although an additional type or overprinting of later immediate burial dolomitization cannot be excluded. Formation of the moulds is attributed mainly to the dissolution of undolomitized fossil cores, most typically stromatoporoids. Geochemical modelling indicates that carboxylic acid fluids have the highest potential for dissolving residual calcite in this case. Geochemical models consistent with this analysis and interpretations can reproduce the Secondary porosite and suggest a viable dolomitization process for the localities studied.
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development of Secondary Porosity in the fairholme carbonate complex southwest alberta canada
Journal of Geochemical Exploration, 2006Co-Authors: Veerle Vandeginste, Rudy Swennen, R M Ellam, Kirk G Osadetz, Sarah A Gleeson, Francois RoureAbstract:Abstract Because of their economic importance as hydrocarbon reservoirs, the Upper Devonian dolomitized carbonate reefs in southwest Alberta have been the subject of several studies. Still, there is no consensus on the process of matrix dolomitization and furthermore, the process of vug development is not often addressed. The studied outcrops show features of an early diagenetic matrix-selective dolomitization by a Late Devonian seawater-derived fluid. Seepage reflux dolomitization combined with latent reflux is proposed, which best explains most chemical characteristics. The cements in the vugs are precipitated from warm saline, 87 Sr-enriched fluids and testify to thermogenic sulphate reduction based on the presence of sulphur, CO 2 and H 2 S in inclusions, relatively high homogenization temperatures and depleted δ 13 C values, which sets constraints on the timing of vug formation. Secondary Porosity may be created by the mixing of formation water with a tectonically and topographically driven fluid and by the dissolution of anhydrite nodules.
Ralf Gellert - One of the best experts on this subject based on the ideXlab platform.
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provenance and diagenesis of the evaporite bearing burns formation meridiani planum mars
Earth and Planetary Science Letters, 2005Co-Authors: S M Mclennan, J F Bell, Wendy M Calvin, Philip R Christensen, Benton C Clark, P A De Souza, J D Farmer, W H Farrand, David A Fike, Ralf GellertAbstract:Abstract Impure reworked evaporitic sandstones, preserved on Meridiani Planum, Mars, are mixtures of roughly equal amounts of altered siliciclastic debris, of basaltic provenance (40 ± 10% by mass), and chemical constituents, dominated by evaporitic minerals (jarosite, Mg-, Ca-sulfates ± chlorides ± Fe-, Na-sulfates), hematite and possibly Secondary silica (60 ± 10%). These chemical constituents and their relative abundances are not an equilibrium evaporite assemblage and to a substantial degree have been reworked by aeolian and subaqueous transport. Ultimately they formed by evaporation of acidic waters derived from interaction with olivine-bearing basalts and subsequent diagenetic alteration. The rocks experienced an extended diagenetic history, with at least two and up to four distinct episodes of cementation, including stratigraphically restricted zones of recrystallization and Secondary Porosity, non-randomly distributed, highly spherical millimeter-scale hematitic concretions, millimeter-scale crystal molds, interpreted to have resulted from dissolution of a highly soluble evaporite mineral, elongate to sheet-like vugs and evidence for minor synsedimentary deformation (convolute and contorted bedding, possible teepee structures or salt ridge features). Other features that may be diagenetic, but more likely are associated with relatively recent meteorite impact, are meter-scale fracture patterns, veins and polygonal fractures on rock surfaces that cut across bedding. Crystallization of minerals that originally filled the molds, early cement and sediment deformation occurred syndepositionally or during early diagenesis. All other diagenetic features are consistent with formation during later diagenesis in the phreatic (fluid saturated) zone or capillary fringe of a groundwater table under near isotropic hydrological conditions such as those expected during periodic groundwater recharge. Textural evidence suggests that rapidly formed hematitic concretions post-date the primary mineral now represented by crystal molds and early pore-filling cements but pre-date Secondary moldic and vug Porosity. The second generation of cements followed formation of Secondary Porosity. This paragenetic sequence is consistent with an extended history of syndepositional through post-depositional diagenesis in the presence of a slowly fluctuating, chemically evolving, but persistently high ionic strength groundwater system.
Xun Kang - One of the best experts on this subject based on the ideXlab platform.
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diagenetic constraints on the heterogeneity of tight sandstone reservoirs a case study on the upper triassic xujiahe formation in the sichuan basin southwest china
Marine and Petroleum Geology, 2017Co-Authors: Wenxuan Hu, Xiaolin Wang, Qingsong Tang, Haiguang Wu, Xun KangAbstract:Abstract Heterogeneity is an essential feature of tight sandstones because it is directly related to reservoir quality. The Upper Triassic Xujiahe Formation in the Sichuan Basin was used as a case study to analyse the diagenetic constraints on the heterogeneity of tight sandstone reservoirs. The three main diagenetic processes of interest are mechanical compaction, cementation, and dissolution. A dissolution facies, quartz cement facies, and carbonate cement facies present sequentially from the centre to the margin of sand bodies. Abundant feldspars and rock fragments were dissolved to form Secondary Porosity or filled by carbonate cement. Authigenic chlorite coatings, generated from eogenesis to the deep burial stage, are thickest in high-Porosity-samples. The δ 13 C of carbonate cement ranges from −10.56‰ to 1.15‰ (PDB), suggesting multiple sources of carbon, including carbonate fragments, early inorganic carbonate cement, and organically derived CO 2 . Based on δ 18 O, carbonate cementation occurred from 33 °C to 110 °C. Microthermometric data of aqueous inclusions indicate that quartz cement precipitated at a temperature range of 120 °C–140 °C. A summary model of the diagenetic constraints on the heterogeneity of sandstones was constructed. The spatial distribution of digenetic facies is controlled by differences in fluid flow velocity and pH. Fluids, especially hydrocarbons, migrated preferentially within the centre of sand bodies, and caused dissolution. Dissolution generated Secondary Porosity and provided materials for authigenic mineral precipitation. Carbonate fragments were better preserved and superimposed with later carbonate cement along the sandstone-mudstone boundary. Quartz overgrowths formed after carbonate cementation, and developed in the transition zone between the intervals of carbonate cementation and dissolution. Consequently, the reservoir quality of the Xujiahe sandstones decreases gradually moving from the centre to the margin of the sand bodies.
D P Serrano - One of the best experts on this subject based on the ideXlab platform.
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synthesis strategies in the search for hierarchical zeolites
Chemical Society Reviews, 2013Co-Authors: D P Serrano, J M Escola, P PizarroAbstract:Great interest has arisen in the past years in the development of hierarchical zeolites, having at least two levels of porosities. Hierarchical zeolites show an enhanced accessibility, leading to improved catalytic activity in reactions suffering from steric and/or diffusional limitations. Moreover, the Secondary Porosity offers an ideal space for the deposition of additional active phases and for functionalization with organic moieties. However, the Secondary surface represents a discontinuity of the crystalline framework, with a low connectivity and a high concentration of silanols. Consequently, hierarchical zeolites exhibit a less “zeolitic behaviour” than conventional ones in terms of acidity, hydrophobic/hydrophilic character, confinement effects, shape-selectivity and hydrothermal stability. Nevertheless, this Secondary surface is far from being amorphous, which provides hierarchical zeolites with a set of novel features. A wide variety of innovative strategies have been developed for generating a Secondary Porosity in zeolites. In the present review, the different synthetic routes leading to hierarchical zeolites have been classified into five categories: removal of framework atoms, surfactant-assisted procedures, hard-templating, zeolitization of preformed solids and organosilane-based methods. Significant advances have been achieved recently in several of these alternatives. These include desilication, due to its versatility, dual templating with polyquaternary ammonium surfactants and framework reorganization by treatment with surfactant-containing basic solutions. In the last two cases, the materials so prepared show both mesoscopic ordering and zeolitic lattice planes. Likewise, interesting results have been obtained with the incorporation of different types of organosilanes into the zeolite crystallization gels, taking advantage of their high affinity for silicate and aluminosilicate species. Crystallization of organofunctionalized species favours the formation of organic–inorganic composites that, upon calcination, are transformed into hierarchical zeolites. However, in spite of this impressive progress in novel strategies for the preparation of hierarchical zeolites, significant challenges are still ahead. The overall one is the development of methods that are versatile in terms of zeolite structures and compositions, capable of tuning the Secondary Porosity properties, and being scaled up in a cost-effective way. Recent works have demonstrated that it is possible to scale-up easily the synthesis of hierarchical zeolites by desilication. Economic aspects may become a significant bottleneck for the commercial application of hierarchical zeolites since most of the synthesis strategies so far developed imply the use of more expensive procedures and reagents compared to conventional zeolites. Nevertheless, the use of hierarchical zeolites as efficient catalysts for the production of high value-added compounds could greatly compensate these increased manufacturing costs.
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hierarchical zeolites with enhanced textural and catalytic properties synthesized from organofunctionalized seeds
Chemistry of Materials, 2006Co-Authors: D P Serrano, J A Aguado, J M Escola, And Jose M Rodriguez, A PeralAbstract:A novel method for the synthesis of hierarchical zeolites has been developed, based on perturbing the crystal growth by organo-functionalization of the zeolite seeds. These materials present unique properties, such as a Secondary Porosity, enhanced surface area, and high catalytic activity for the conversion of bulky molecules.
S M Mclennan - One of the best experts on this subject based on the ideXlab platform.
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volumes and orientation of Secondary Porosity in the burns formation meridiani planum mars
LPI, 2007Co-Authors: S M Perl, S M Mclennan, J P Grotzinger, K E HerkenhoffAbstract:Introduction: Development of Secondary Porosity occurs post-depositionally in sedimentary rocks during mineral transformation, rock fracture, and mineral dissolution. The timing and shape of Secondary pores provide constraints on the record of fluid flow through sedimentary rocks. For comparison, in terrestrial carbonate rocks, Secondary Porosity, where present, typically is in the range of 5-15% by volume whereas in sandstones it may reach 15-30% [1]. Sedimentary rocks studied by the Opportunity rover reveal evidence of diagenetic processes including formation of hematite spherules, recrystallization, crystal molds, and others. McLennan et al. [2] noted the presence of void spaces within the Burns formation that were interpreted as Secondary Porosity formed by dissolution of soluble salts during groundwater recharge. The purpose of this study is to quantify the volumes, sizes, and spatial orientations of Secondary pores and evaluate if there is any relationship with the type of Secondary Porosity. Secondary Porosity Classification: Three types of Secondary Porosity have been identified (Fig. 1): crystal moldic Porosity (typically fabric selective), sheet-like to elongated vug, or channel Porosity (typically non-fabric selective), and a modified (enlarged) version of both. Crystal Mold Porosity: One of the first diagenetic textures recognized in the Burns formation were mmsized "vugs", noted by Squyres, et al. [4]. Using the Porosity classification of Choquette and Pray [1], these are more precisely termed crystal moldic Porosity. The average size of these pores have a width of 1 (s.d.=0.5) mm and a length of 5 (s.d.=3) mm. and their tabular shape suggests the former presence of a monoclinic mineral. The amount of crystal mold Porosity has been found to vary considerably from place to place. These pores have been interpreted to represent dissolution of a highly soluble mineral such as Mg-sulfates, ferrous sulfates or chlorides [2,4]. Elongated to Sheet-like Vug and Channel Porosity: These pore types are related and occur in patterns that appear to both parallel and cut across bedding. Choquette and Pray [1] define channel Porosity as nonfabric selective Secondary Porosity where length to width ratios are greater than ten. Many of the pores observed in the Burns formation are elongate but have length to width ratios less than ten. Although many of these vugs cut across primary bedding fabrics, in many places they also appear to preferentially align along bedding thus giving them a mixed fabric selective – non-fabric selective character. Accordingly, these have been termed elongate to sheet-like vugs. They are interpreted to represent dissolution of relatively soluble mineral phase(s) such as Mg-sulfates [2]. Pore Modification: Although less common we have observed the presence of significantly enlarged pores. These oversized vugs are considerably larger than the size of regular vugs and are found to modify each of the two types of Secondary Porosity. The amount of modification varies from rock to rock. The process of pore modification occurs mostly within cmto dm-scale stratigraphic zones in the upper part of the Burns formation, notably in the vicinity of the
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provenance and diagenesis of the evaporite bearing burns formation meridiani planum mars
Earth and Planetary Science Letters, 2005Co-Authors: S M Mclennan, J F Bell, Wendy M Calvin, Philip R Christensen, Benton C Clark, P A De Souza, J D Farmer, W H Farrand, David A Fike, Ralf GellertAbstract:Abstract Impure reworked evaporitic sandstones, preserved on Meridiani Planum, Mars, are mixtures of roughly equal amounts of altered siliciclastic debris, of basaltic provenance (40 ± 10% by mass), and chemical constituents, dominated by evaporitic minerals (jarosite, Mg-, Ca-sulfates ± chlorides ± Fe-, Na-sulfates), hematite and possibly Secondary silica (60 ± 10%). These chemical constituents and their relative abundances are not an equilibrium evaporite assemblage and to a substantial degree have been reworked by aeolian and subaqueous transport. Ultimately they formed by evaporation of acidic waters derived from interaction with olivine-bearing basalts and subsequent diagenetic alteration. The rocks experienced an extended diagenetic history, with at least two and up to four distinct episodes of cementation, including stratigraphically restricted zones of recrystallization and Secondary Porosity, non-randomly distributed, highly spherical millimeter-scale hematitic concretions, millimeter-scale crystal molds, interpreted to have resulted from dissolution of a highly soluble evaporite mineral, elongate to sheet-like vugs and evidence for minor synsedimentary deformation (convolute and contorted bedding, possible teepee structures or salt ridge features). Other features that may be diagenetic, but more likely are associated with relatively recent meteorite impact, are meter-scale fracture patterns, veins and polygonal fractures on rock surfaces that cut across bedding. Crystallization of minerals that originally filled the molds, early cement and sediment deformation occurred syndepositionally or during early diagenesis. All other diagenetic features are consistent with formation during later diagenesis in the phreatic (fluid saturated) zone or capillary fringe of a groundwater table under near isotropic hydrological conditions such as those expected during periodic groundwater recharge. Textural evidence suggests that rapidly formed hematitic concretions post-date the primary mineral now represented by crystal molds and early pore-filling cements but pre-date Secondary moldic and vug Porosity. The second generation of cements followed formation of Secondary Porosity. This paragenetic sequence is consistent with an extended history of syndepositional through post-depositional diagenesis in the presence of a slowly fluctuating, chemically evolving, but persistently high ionic strength groundwater system.