Spatial distribution and evolution of porosity in a heterogeneous clay-rich fault core

Sedimentary clay rocks present impermeable, low-porosity formations, often having a seal function to hydrocarbon reservoirs and geological repositories. Due to their impermeable properties, these shale beds can act as a barrier to fluid flow. However, shale formations are intruded by fault zones with permeabilities that can differ of several orders of magnitudes with respect to the undeformed host rock. The fault core comprises of several structures, including breccias, cataclasites and one or several slip surfaces. The slip surface of a fault consists of clay gouge that is heterogeneous material with anisotropic properties in terms of porosity and permeability. The fault core with clay-gouge can act as a barrier or as a lengthwise conduit to fluid flow, depending on physical and chemical properties of a fault. For these reasons, the distribution of porosity in fault core is a key parameter for many applications, including hydrocarbon reservoir capacity, geothermal energy projects and geological repositories for CO2 or high-level radioactive waste. The objective of this work is to combine information on spatial distribution of porosity provided by the 14C-PMMA autoradiography method with the mineralogical information provided by a comprehensive SEM-EDS elemental mapping and to define the porosity variations in and around fault gouges and connect them to processes in a fault system. The samples used in this study were taken from a small-scale vertical strike-slip fault in an argillaceous shale formation at the Tournemire underground research laboratory, Southern France. The results display significant variations in porosity and mineralogy along the studied gouge zone, most probably due to a polyphased tectonic history and paleo-fluid migrations. The studied gouge expresses low porosities in the central part, but porosity values increase significantly in the margins of the gouge. Moreover, the mineralogical changes indicate sealing/healing effects and past hydrothermal activities within the fault zone. The sealing effect is displayed by distribution of calcium as calcite, which is concurrent with lower porosities around the gouge zone. The EDS analysis reveals the zonality of iron and existence of zinc sulphide and barium sulphate inside the gouge, further suggesting hydrothermal activity in the past. Furthermore, the zonality of iron is coherent with different porosity areas as it has formed concentration bands around the areas of low-porosity gouge. Even though the observed porosity variations occur in only a centimetre-wide gouge zone, the higher porosity sections may imply pathways for fluid flow if the fault is reactivated

Sealing, healing and fluid flow in clay rocks : Insights on episodic flow events in fault zones

The porosity distribution and mineralogical changes in a clay-rich fault core from the Tournemire underground research laboratory are analyzed to determine the mechano-chemical processes in a small-scale vertical strike-slip fault. The results display significant spatial variations in porosity and mineralogy along different gouge zones due to a polyphased tectonic history combined with complex paleo-fluid migrations. Porosity values increase from the center of the gouges to their borders indicating diffusive sealing/healing effects and past hydrothermal activities. The healing and thus the strengthening of the fault is marked by an increase of calcium content, which is concurrent with lower porosities around the gouge zone. Chemical mapping in the gouges reveal clay alteration, iron zonality and the presence of zinc sulphide as well as barium sulphate inside the gouge, further suggesting past hydrothermal activity. Finally, even though the observed porosity variations only occur in subcentimeter-thick gouge bands, the higher porosity sections are pathways for fluid flow during fault activity. © 5th International Conference on Fault and Top Seals 2019. All Rights Reserved.Peer reviewe

Porosity distribution in a heterogeneous clay-rich fault core by image processing of 14C-PMMA autoradiographs and Scanning Electron Microscopy

Shale formations are considered by a number of countries as the most suitable media to dispose of high-level radioactive waste. This is mainly due to the impermeable, self-sealing, chemical reducing, and sorption properties that tend to retard radionuclide migration. However, shale formations can also contain highly connected fault zones with permeabilities that can differ of several orders of magnitudes with respect to the undeformed host rock. The objective of this work is to use the 14C-PMMA autoradiography method combined with SEM-EDS measurements to understand the porosity variations in and around fault gouges and to define their relationship to mechano-chemical processes. The studied samples were taken from a low permeability shale in a small-scale vertical strike-slip fault at the Tournemire underground research laboratory. Results display significant variations in porosity and mineralogy along the studied gouge zone due to polyphased tectonics and paleo-fluid circulations.Shale formations are considered by a number of countries as the most suitable media to dispose of high-level radioactive waste. This is mainly due to the impermeable, self-sealing, chemical reducing, and sorption properties that tend to retard radionuclide migration. However, shale formations can also contain highly connected fault zones with permeabilities that can differ of several orders of magnitudes with respect to the undeformed host rock. The objective of this work is to use the 14C-PMMA autoradiography method combined with SEM-EDS measurements to understand the porosity variations in and around fault gouges and to define their relationship to mechano-chemical processes. The studied samples were taken from a low permeability shale in a small-scale vertical strike-slip fault at the Tournemire underground research laboratory. Results display significant variations in porosity and mineralogy along the studied gouge zone due to polyphased tectonics and paleo-fluid circulations.Peer reviewe

Next-Generation EU DataGrid Data Management Services

We describe the architecture and initial implementation of the next-generation of Grid Data Management Middleware in the EU DataGrid (EDG) project. The new architecture stems out of our experience and the users requirements gathered during the two years of running our initial set of Grid Data Management Services. All of our new services are based on the Web Service technology paradigm, very much in line with the emerging Open Grid Services Architecture (OGSA). We have modularized our components and invested a great amount of effort towards a secure, extensible and robust service, starting from the design but also using a streamlined build and testing framework. Our service components are: Replica Location Service, Replica Metadata Service, Replica Optimization Service, Replica Subscription and high-level replica management. The service security infrastructure is fully GSI-enabled, hence compatible with the existing Globus Toolkit 2-based services; moreover, it allows for fine-grained authorization mechanisms that can be adjusted depending on the service semantics.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla,Ca, USA, March 2003 8 pages, LaTeX, the file contains all LaTeX sources - figures are in the directory "figures

Akustiikan visualisointi virtuaaliympäristössä

This thesis presents implementation of acoustics visualization software used in immersive virtual environment. It is discussed how such a system is being designed, implemented, and what problems occurred during the implementation. The system is found useful for architects and acousticians for studying room acoustics and for visualizing acoustical problems. The implementation of the acoustic visualization system is set as the primary objective for the thesis. Secondary objectives are to study visualization of acoustics and try to find out if immersive visualization is more useful than traditional visualization methods. The needed knowledge about acoustics, virtual reality, and visualization are discussed. All this background information is used in the implementation. The software implementation is explained step by step including discussion about choosing the ray tracing as the most efficient visualization method for acoustic visualization. Other visualization methods are found to produce similar visualization or to be computationally too heavy for the target environment. The performance is sufficient after optimization. The main visualizations are static and animated with either ray or particle visualizations. The main contribution of this thesis is implementation of acoustics visualization system that can be used in immersive virtual environment. Earlier, only desktop systems have been available. However, the benefit of the immersive visualization is not being measured in this thesis. Instead, previous work on presence research is being evaluated and it is found that studying the gain from the immersiviness had to be left out for future work.Tässä diplomityössä esitellään akustiikan visualisointijärjestelmä, jota käytetään immersiivisessä keinotodellisuushuoneessa. Systeemin suunnittelu, toteutus ja toteutukseen liittyneet ongelmat esitellään yksityiskohtaisesti. Visualisointijärjestelmä havaittiin erityisen hyödylliseksi arkkitehdeille ja akustiikoille huoneakustiikan tutkimiseen ja akustisten ongelmien visualisointiin. Diplomityön ensisijainen tavoite on implementoida immersiivinen akustiikan visualisointijärjestelmä. Toissijaisia tavoitteita on tutkia akustiikan visualisointia ja tutkia onko immersiivisestä visualisoinnista hyötyä perinteisiin visualisointimenetelmiin verrattuna. Järjestelmän toteutusta varten tarvittava pohjatieto akustiikasta, keinotodellisuudesta ja visualisoinnista esitellään tarkasti. Sateenseuranta valittiin parhaaksi tekniikaksi akustiikan visualisointia varten. Myös muita tekniikoita käsitellään, mutta niitä ei toteutettu koska niillä saataisiin aikaan vain hyvin samanlaisia visualisointeja kuin sateenseurannalla tai niiden tehokkuus olisi liian heikko käytettävissä olevaa virtuaaliympäristöä varten. Optimointien jälkeen järjestelmän tehokkuus on riittävällä tasolla. Erilaiset toteutuneet visualisoinnit jakautuvat karkeasti neljään eri ryhmään jotka ovat staattiset ja animoidut visualisoinnit yhdistettynä säde- ja partikkelivisualisointeihin. Diplomityön tärkein kontribuutio on immersiivisen akustiikan visualisointijärjestelmän toteutus. Aiemmin vastaavia järjestelmiä pystyi käyttämään vain pöytätietokoneilla. Kuitenkin immersiivisen visualisoinnin varsinaista hyötyä ei tässä työssä tutkittu, koska tämä työ jätettiin tämän diplomityön ulkopuolelle

Architecture and operational model for smart campus digital infrastructure

Abstract Nations and cities are eagerly joining the global trend of transition to digitized society. Through digitalization, societies aim to streamline their key functions and to develop modern services to inhabitants. 5G wireless networks are being built globally with lots of expectations put on them. It is anticipated that at the first phase of 5G, the technology will benefit the most different verticals like factories, hospitals and campuses. Universities have likewise awoken to establish digitalization projects to respond to the disruption of education and to overcome in the growing global competition. The transition to digital campus will inevitably rely on campus ICT and IoT infrastructures. Additionally, the number of terminals, devices, sensors and robots will multiply. This article proposes a technical architecture for future Smart Campus consisting of 5G and IoT networks complemented by distributed computing and data analytics. Increasing complexity of digital environment calls for a specific actor to operate the Smart Campus infrastructure and also services, which has not been widely discussed. It is foreseen that the university IT Administration is probably not willing to adopt the responsibility of enlarging infra and growing number of devices. Similarly, mobile network operators are not seen appropriate to take this role being commonly profiled to offer merely connectivity. To tackle this question, a novel operational model for the Smart Campuses is presented based on the recently proposed micro operator concept. Moreover, a case study of the University of Oulu campus is presented, where smart technology in the form of 5G test network has been deployed

Formation and transformation of Fe(III)- and Ca-precipitates in aqueous solutions and effects on phosphate retention over time

Exfiltration of anoxic phosphate-rich groundwater into surface water leads to the oxidation of dissolved Fe(II) and the formation of Fe(III)-precipitates that can retain phosphate (PO₄) and thereby attenuate eutrophication. Fresh Fe(III)-precipitates transform into more stable phases over time, and retained PO₄ may be released again. In parallel, CO₂ outgassing can promote the formation of Ca-phosphates or -carbonates that also sequester PO₄. In laboratory experiments, we studied the effects of Mg, Ca, silicate (SiO₄) and PO₄ on these processes. Fresh Fe(III)-precipitates were formed in bicarbonate-buffered aqueous solutions at pH ∼ 7.0 via the oxidation of 0.5 mM Fe(II) in the presence of 0.15 or 0.025 mM PO₄, at Mg or Ca concentrations of 0, 0.4, 1.2 or 4 mM and in the absence or presence of 0.5 mM SiO₄. After CO₂ outgassing, the suspensions were allowed to age for 100 d at pH ∼ 8. Changes in the composition and structure of Fe(III)- and Ca-precipitates over time were probed with spectroscopic and microscopic techniques and were linked to variations in the retention of PO₄. The oxidation of Fe(II) led to effective PO₄ removal via the formation of Fe(III)-precipitates that consisted of amorphous (Ca-)Fe(III)-phosphate ((Ca)FeP), ferrihydrite (Fh) and, in SiO₄-free treatments, lepidocrocite (Lp). During aging, FeP and Fh that had formed in the absence of Mg, Ca and SiO₄ rapidly and nearly completely transformed into Lp. Via effects on molecular- and nanoscale precipitate structure, Mg slowed down FeP transformation into Fh, stabilized Fh, and decreased the crystallinity of Lp (in SiO₄-free suspensions), Ca stabilized CaFeP against transformation into Fh, and SiO₄ stabilized Fh and (Ca)FeP. Core/shell CaFeP/Fh particles formed in electrolytes that contained Ca and SiO₄ hardly transformed within 100 d. Calcite only formed at low dissolved PO₄ concentrations and, by incorporation of PO₄, contributed to PO₄ retention. Higher levels of dissolved PO₄ inhibited calcite formation but could induce Ca-phosphate precipitation. Differences in precipitate formation and transformation pathways and kinetics were reflected in the extents of PO₄ release over the 100-d aging period, ranging from rapid release of 77% of the total PO₄ in the treatment without Mg, Ca and SiO₄ at 0.15 mM total PO₄ to slow release of only 0.1% of the total PO at initial concentrations of 4 mM Ca, 0.5 mM SiO₄, and 0.025 mM PO₄. In summary, this study reveals the conditions and the extents and timescales over which Fe(III)- and Ca-precipitates form and transform and how these processes affect PO₄ immobilization in near-neutral natural waters. The detailed new insights into the coupling between Fe(III)- and Ca-precipitate formation and into the interdependent effects of Mg, Ca, SiO₄ and PO₄ are not only relevant with respect to PO₄ but also with respect to the cycling of trace elements in natural and engineered systems.ISSN:0016-7037ISSN:1872-953