Éditeur(s) : HAL CCSD
Résumé : International audience
During the last decade, GIS have suffered of the lack of structured information and semantic definition of the data. The numerous origins of the data and the spatial localization of the object inferred many inconsistencies among them. Indeed, the way to collect data and the level of sampling of the boundary differ from one application to another and from one expert to another. This leads to different representations of the same reality and different models of semantically identical objects or boundaries. To allow the matching of the objects, or parts of the objects, when combining different information layers we introduced a conceptual layer which described a scene with concepts and spatial relationships based on the definition of an ontology. This layer allows detecting and solving conflicts between the common boundaries of two objects. We present in this paper the specification and the way to build and use the ontology.
Geoprocessing proceedings
Gosier, Guadeloupe

hal-00602257
https://hal.archives-ouvertes.fr/hal-00602257

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Much debate exists concerning the strength distribution of the continental lithosphere, how it controls lithosphere-scale strain localization and hence enables plate tectonics. No rheological model proposed to date is comprehensive enough to describe both the weakness of plate boundary and rigid-like behaviour of plate interiors. Here we show that the duality of strength of the lithosphere corresponds to different stages of microstructural evolution. Geological constraints on lithospheric strength and large strain numerical experiments reveal that the development of layers containing weak minerals and the onset of grain boundary sliding upon grain size reduction in olivine cause strain localisation and reduce strength in the crust and subcontinental mantle, respectively. The positive feedback between weakening and strain localization leads to the progressive development of weak plate boundaries while plate interiors remain
ISSN: 0040-1951

insu-00949213
https://hal-insu.archives-ouvertes.fr/insu-00949213
https://hal-insu.archives-ouvertes.fr/insu-00949213/document
https://hal-insu.archives-ouvertes.fr/insu-00949213/file/Gueydan_et_al_2014.pdf
DOI : 10.1016/j.tecto.2014.02.005

Éditeur(s) : HAL CCSD American Geophysical Union (AGU)
Résumé : International audience
The Pyrenean peridotites (lherzolites) form numerous small bodies of subcontinental mantle, a few meters to 3 km across, exposed within the narrow north Pyrenean zone (NPZ) of Mesozoic sediments paralleling the north Pyrenean Fault. Recent studies have shown that mantle exhumation occurred along the future NPZ during the formation of the Albian-Cenomanian Pyrenean basins in relation with detachment tectonics. This paper reviews the geological setting of the Pyrenean lherzolite bodies and reports new detailed field data from key outcrops in the Bearn region. Only two types of geological settings have to be distinguished among the Pyrenean ultramafic bodies. In the first type (sedimented type or S type), the lherzolites occur as clasts of various sizes, ranging from millimetric grains to hectometric olistoliths, within monogenic or polymictic debris flow deposits of Cretaceous age, reworking Mesozoic sediments in dominant proportions as observed around the Lherz body. In the second type (tectonic type or T type), the mantle rocks form hectometric to kilometric slices associated with crustal tectonic lenses. Both crustal and mantle tectonic lenses are in turn systematically associated with large volumes of strongly deformed Triassic rocks and have fault contacts with units of deformed Jurassic and Lower Cretaceous sediments belonging to the cover of the NPZ. These deformed Mesozoic formations are not older that the Aptian-early Albian. They are unconformably overlain by the Albian-Cenomanian flysch formations and have experienced high temperature-low pressure mid-Cretaceous metamorphism at variable grades. Such a tectonic setting characterizes most of the lherzolite bodies exposed in the western Pyrenees. These geological data first provide evidence of detachment tectonics leading to manle exhumation and second emphasize the role of gravity sliding of the Mesozoic cover in the preorogenic evolution of the Pyrenean realm. In the light of such evidence, a simple model of basin development can be inferred, involving extreme thinning of the crust, and mantle uprising along a major detachment fault. We demonstrate coeval development of a crust-mantle detachment fault and generalized gravitational sliding of the Mesozoic cover along low-angle faults involving Triassic salt deposits as a tectonic sole. This model accounts for the basic characteristics of the precollisional rift evolution in the Pyrenean realm.
ISSN: 0278-7407

hal-00512818
https://hal.archives-ouvertes.fr/hal-00512818
DOI : 10.1029/2009TC002588

Éditeur(s) : HAL CCSD Frontiers
Résumé : International audience
The generation of handwriting is a complex neuromotor skill requiring the interaction of many cognitive processes. It aims at producing a message to be imprinted as an ink trace left on a writing medium. The generated trajectory of the pen tip is made up of strokes superimposed over time. The Kinematic Theory of rapid human movements and its family of lognormal models provide analytical representations of these strokes, often considered as the basic unit of handwriting. This paradigm has not only been experimentally confirmed in numerous predictive and physiologically significant tests but it has also been shown to be the ideal mathematical description for the impulse response of a neuromuscular system. This latter demonstration suggests that the lognormality of the velocity patterns can be interpreted as reflecting the behavior of subjects who are in perfect control of their movements. To illustrate this interpretation, we present a short overview of the main concepts behind the Kinematic Theory and briefly describe how its models can be exploited, using various software tools, to investigate these ideal lognormal behaviors. We emphasize that the parameters extracted during various tasks can be used to analyze some underlying processes associated with their realization. To investigate the operational convergence hypothesis, we report on two original studies. First, we focus on the early steps of the motor learning process as seen as a converging behavior toward the production of more precise lognormal patterns as young children practicing handwriting start to become more fluent writers. Second, we illustrate how aging affects handwriting by pointing out the increasing departure from the ideal lognormal behavior as the control of the fine motricity begins to decline. Overall, the paper highlights this developmental process of merging toward a lognormal behavior with learning, mastering this behavior to succeed in performing a given task, and then gradually deviating from it with aging.
ISSN: 1664-1078

hal-01098124
https://hal.archives-ouvertes.fr/hal-01098124
DOI : 10.3389/fpsyg.2013.0094

Éditeur(s) : HAL CCSD Oxford University Press
Résumé : International audience
The BioMart Community Portal (www.biomart.org) is a community-driven effort to provide a unified interface to biomedical databases that are distributed worldwide. The portal provides access to numerous database projects supported by 30 scientific organizations. It includes over 800 different biological datasets spanning genomics, proteomics, model organisms, cancer data, ontology information and more. All resources available through the portal are independently administered and funded by their host organizations. The BioMart data federation technology provides a unified interface to all the available data. The latest version of the portal comes with many new databases that have been created by our ever-growing community. It also comes with better support and extensibility for data analysis and visualization tools. A new addition to our toolbox, the enrichment analysis tool is now accessible through graphical and web service interface. The BioMart community portal averages over one million requests per day. Building on this level of service and the wealth of information that has become available, the BioMart Community Portal has introduced a new, more scalable and cheaper alternative to the large data stores maintained by specialized organizations.
ISSN: 0305-1048

hal-01146849
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01146849
DOI : 10.1093/nar/gkv350
PUBMED : 25897122

Éditeur(s) : HAL CCSD Optical Society of America
Résumé : International audience
A linear least square (LLS) method is proposed to process polarization dependent SHG intensity analysis at pixel-resolution level in order to provide an analytic solution of nonlinear susceptibility χ(2) coefficients and of fibril orientation. This model is applicable to fibrils with identical orientation in the excitation volume. It has been validated on type I collagen fibrils from cell-free gel, tendon and extracellular matrix of F1 biliary epithelial cells. LLS is fast (a few hundred milliseconds for a 512 × 512 pixel image) and very easy to perform for non-expert in numerical signal processing. Theoretical simulation highlights the importance of signal to noise ratio for accurate determination of nonlinear susceptibility χ(2) coefficients. The results also suggest that, in addition to the peptide group, a second molecular nonlinear optical hyperpolarizability β contributes to the SHG signal. Finally from fibril orientation analysis, results show that F1 cells remodel extracellular matrix collagen fibrils by changing fibril orientation, which might have important physiological function in cell migration and communication.
ISSN: 1094-4087

hal-01139871
https://hal.archives-ouvertes.fr/hal-01139871
DOI : 10.1364/OE.23.013309
PUBMED : 26074581

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Properly assessing the extent and magnitude of fault ruptures associated with large earthquakes is critical for understanding fault behavior and associated hazard. Submarine faults can trigger tsunamis, whose characteristics are defined by the geometry of seafloor displacement, studied primarily through indirect observations (e.g., seismic event parameters, seismic profiles, shipboard bathymetry, coring) rather than direct ones. Using deep-sea vehicles, we identify for the first time a marker of coseismic slip on a submarine fault plane along the Roseau Fault (Lesser Antilles), and measure its vertical displacement of ∼0.9 m in situ. We also map recent fissuring and faulting of sediments on the hangingwall, along ∼3 km of rupture in close proximity to the fault's base, and document the reactivation of erosion and sedimentation within and downslope of the scarp. These deformation structures were caused by the 2004 M w 6.3 Les Saintes earthquake, which triggered a subsequent tsunami. Their characterization informs estimates of earthquake recurrence on this fault and provides new constraints on the geometry of fault rupture, which is both shorter and displays locally larger coseismic displacements than available model predictions that lack field constraints. This methodology of detailed field observations coupled with near-bottom geophysical surveying can be readily applied to numerous submarine fault systems, and should prove useful in evaluating seismic and tsunamigenic hazard in all geodynamic contexts.
ISSN: 0012-821X

insu-01557932
https://hal-insu.archives-ouvertes.fr/insu-01557932
https://hal-insu.archives-ouvertes.fr/insu-01557932/document
https://hal-insu.archives-ouvertes.fr/insu-01557932/file/EPSL-2006-escartin.pdf
DOI : 10.1016/j.epsl.2016.06.024

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Wallace (1951) and Bott (1959) were the first to introduce the idea that the slip on each fault surface has the same direction and sense as the maximum shear stress resolved on that surface. However, this simplified hypothesis is questionable since fault mechanical interactions may induce slip reorientations. Earlier numerical geomechanical models confirmed that the slickenlines (slip vectors) are not necessarily parallel to the maximum resolved shear stress but are consistent with local stress perturbations. This leads us to ask as to what extent the Wallace and Bott simplifications are reliable as a basis hypothesis for stress inversion from fault slip data. Here, a geomechanical multi-parametric study using a 3D boundary element method, covering (i) fault geometries such as intersected faults or corrugated fault surfaces, (ii) the full range of Andersonian state of stress, (iii) fault friction, (iv) fault fluid pressure, (v) half space effect and (vi), rock properties, is performed in order to understand the effect of each parameter on the misfit angle between geomechanical slip vectors and the resolved shear stresses. It is shown that significant misfit angles can be found under specific configurations invalidating the Wallace and Bott assumptions, even though fault friction tends to minimize the misfit. We therefore conclude that in such cases, stress inversions based on fault slip data should be interpreted with care.
ISSN: 0040-1951

hal-01218418
https://hal.archives-ouvertes.fr/hal-01218418
DOI : 10.1016/j.tecto.2015.06.030

Éditeur(s) : HAL CCSD
Résumé : International audience
BACKGROUND: Numerous studies have linked prenatal traffic-related air pollution exposure to fetal growth. Recently, several studies have suggested exploring this association independently among boys and girls because of potential sex-specific biological vulnerability to air pollution. Residence-based factors can also influence fetal growth by enhancing susceptibility to the toxic effects of air pollution and must also be considered in these relations. OBJECTIVE: We examined sex-specific associations between prenatal air pollution exposure and fetal growth and explored whether they differed by the urban-rural status of maternal residence. METHODS: This study relied on the PELAGIE mother-child cohort (2521 women, Brittany, France, 2002-2006). Fetal growth was assessed through birth weight, head circumference and small weight (SGA) and small head circumference (SHC) for gestational age. Nitrogen dioxide (NO2) concentrations at mothers' homes were estimated by using a land use regression model taking into account temporal variation during pregnancy. Associations between estimated NO2 concentrations and fetal growth were assessed with linear regression or logistic regression models, depending on the outcome investigated. RESULTS: An interquartile range (8.8µgm(-3)) increase in NO2 exposure estimates was associated with a 27.4g (95% CI 0.8 to 55.6) increase in birth weight and a 0.09cm (95% CI 0.00-0.17) significant increase in head circumference, among newborn boys only. Their risks of SGA and SHC were reduced (OR 0.70, 95% CI 0.53-0.92, OR 0.76, 95% CI 0.56-1.03, respectively, for an increase of 8.8µgm(-3)). No statistically significant trends were observed among girls. Urban-rural status modified the effect of air pollution only for SHC and again only for newborn boys. CONCLUSION: Findings from this study confirm the need to consider sex-specific associations between air pollution and fetal growth and to investigate possible mechanisms by which traffic-related air pollution may increase anthropometric parameters at birth
Environmental Research

hal-01205354
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01205354
DOI : 10.1016/j.envres.2015.09.006
PUBMED : 26378737

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
ISSN: 0258-8900

hal-00682343
https://hal.archives-ouvertes.fr/hal-00682343
DOI : 10.1007/s00445-011-0554-0

Éditeur(s) : HAL CCSD EDP Sciences
Résumé : International audience
Aggregation patterns are often visually detected in sets of location data. These clusters may be the result of interesting dynamics or the effect of pure randomness. We build an asymptotically Gaussian test for the hypothesis of randomness corresponding to a homogeneous Poisson point process. We first compute the exact first and second moment of the Ripley K-statistic under the homogeneous Poisson point process model. Then we prove the asymptotic normality of a vector of such statistics for different scales and compute its covariance matrix. From these results, we derive a test statistic that is chi-square distributed. By a Monte-Carlo study, we check that the test is numerically tractable even for large data sets and also correct when only a hundred of points are observed
ISSN: 1292-8100

hal-01502640
https://hal-agroparistech.archives-ouvertes.fr/hal-01502640
DOI : 10.1051/ps/2012027

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The detailed morphology and internal structure of the Calabrian accretionary wedge and adjacent Eastern Sicily margin are imaged in unprecedented detail by a combined dataset of multi-beam bathymetry and high-resolution seismic profiles. The bathymetric data represent the results of 6 recent marine geophysical surveys since 2010 as well as a compilation of earlier surveys presented as a 2 arc-sec (60 m) grid. Several distinct morpho-tectonic provinces are identified including: the deeply incised Malta–Hyblean Escarpment, numerous submarine canyons, broad regions of relatively flat seafloor dominated by fields of sediment waves, the gently undulating anticlinal fold-and-thrust belts of the external Calabrian accretionary wedge and the adjacent portion of the Western Mediterranean Ridge. The Calabrian arc can be divided into 4 domains (from SE to NW): 1) the undeformed Ionian abyssal plain, 2) the external evaporitic wedge, 3) the internal clastic wedge, 4) the Calabrian backstop (Variscan crystalline basement). The Calabrian accretionary wedge can also be divided laterally into two major lobes, the NE- and the SW lobes, and two minor lobes. The kinematics of the limit between the two major lobes is investigated and shown to be sinistral in the external (evaporitic) wedge. A network of radial slip lines within the southernmost external wedge unequivocally demonstrate ongoing dextral displacement of a rigid indenter (representing the corner of the clastic wedge) into the evaporitic wedge thereby confirming the geodynamic model of an active lateral slab tear fault here off eastern Sicily. The slab tear produces a series of major sub-parallel dextral strike-slip faults offshore Mt. Etna and south of the Straits of Messina consistent with the relative motions between Calabria and the Peloritan domain (NE Sicily). Abundant strike-slip faulting, and wide-spread folding and thrusting observed throughout the entire accretionary wedge, indicate regional shortening between the Ionian abyssal plain (foreland) and the Calabrian–Peloritan backstop caused by active subduction.
ISSN: 0012-821X

hal-01523990
https://hal.archives-ouvertes.fr/hal-01523990
DOI : 10.1016/j.epsl.2016.12.020

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
The Maguelone shore extends along the northern coast of the Gulf of Lions, west of the Rhone Delta and east of high-gradient coastal streams that have provided most of the clastic sediments to the Gulf of Lions margin since the early Miocene. This 10 km-wide area is constituted by a small coastal watershed (15 km long) in low-lying carbonate hills, a kilometre-wide marsh, a sandy beach barrier and a shoreface experiencing local low sedimentation rates. This onshore-offshore transition zone is a key area to understand the relationships between erosion, by-pass, deposition and preservation processes. Unlike the neighbouring Rhone deposits that display numerous thick deltaic sequences related to a continuous sediment flux, the Maguelone shore exhibits peculiar sedimentary bodies. The analysis of about 250 km of new VHR seismic profiles acquired over the study area, 9 short cores and outcrops data allowed us to determine the three-dimensional high-resolution geometry of the coastal system tracts from Quaternary to present-day. This revealed dominant denudation processes in the Upstream catchments associated with the formation of incised valleys during Quaternary lowstands. In addition, this study investigates the erosion and deposition mechanisms controlled by littoral hydrodynamics that have been taken place on this shore since the last transgression. In particular, metre-high and hundreds of metre-long sandy bodies constructed by alongshore hydrodynamics were identified and their effect on the morphodynamics of the whole littoral system is discussed. The Maguelone shore can be used as an experimental study for onshore/offshore dynamics under the influence of microtidal wave/current hydrodynamics and very low river-derived sediment flux during a eustatic cycle. Geometry of system tracts across flood plain to shoreface is usually considered to be controlled by relative sea-level changes, and is successfully analysed with 2D sequence stratigraphy cross-shore models. It is observed that in areas like the Maguelone shore, traditional sequence stratigraphy methods might not be fully relevant and need to integrate alongshore hydrodynamical processes.
ISSN: 0025-3227

hal-00421060
https://hal.archives-ouvertes.fr/hal-00421060
DOI : 10.1016/j.margeo.2009.06.008

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Saccharomyces cerevisiae is an established model organism for the molecular analysis of fundamental biological processes. The genomes of numerous strains have been sequenced, and the transcriptome and proteome ofmajor phases during the haploid and diploid yeast life cycle have been determined. However, much less is known about dynamic changes of the proteome when cells switch from mitotic growth to meiotic development. We report a quantitative protein profiling analysis of yeast cell division and differentiation based on mass spectrometry. Information about protein levels was integrated with strand-specific tiling array expression data. We identified a total of 2366 proteins in at least one condition, including 175 proteins showing a statistically significant > 5-fold change across the sample set, and 136 proteins detectable in sporulating but not respiring cells. We correlate protein expression patterns with biological processes and molecular function by Gene Ontology term enrichment, chemoprofiling, transcription interference and the formation of double stranded RNAs by overlapping sense/antisense transcripts. Our work provides initial quantitative insight into protein expression in diploid respiring and differentiating yeast cells. Critically, it associates developmentally regulated induction of antisense long noncoding RNAs and double stranded RNAs with fluctuating protein concentrations during growth and development.
ISSN: 1874-3919

hal-01485858
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01485858
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01485858/document
https://hal-univ-rennes1.archives-ouvertes.fr/hal-01485858/file/Becker%20et%20al.%20-%20The%20protein%20expression%20landscape%20of%20mitosis%20and%20me.pdf
DOI : 10.1016/j.jprot.2016.12.016

Éditeur(s) : HAL CCSD
Résumé : International audience
Numerous social network mining methods have been proposed until now for addressing social mining tasks and specially searching for communities or frequent social patterns. However, the degree of complementarity of these methods has been very little studied. In this paper, we focus on two knowledge extraction processes in social networks: a link-based clustering that may extract social communities and a recent approach that searches for frequent conceptual link involving both clustering and search for frequent social patterns. We explore how the models extracted by each method may match and which potential useful knowledge they may provide. Our objective is to evaluate the potential relationships between communities and frequent conceptual links. For this purpose, we propose a set of measures for evaluating the degree to which these patterns extracted from the same dataset are matching. Our approach is applied on two datasets and demonstrates the importance of considering simultaneously various kinds of knowledge and their complementarity.
IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining
Niagara falls, Canada

hal-00874351
https://hal.archives-ouvertes.fr/hal-00874351

Éditeur(s) : HAL CCSD
Résumé : International audience
Characterizing the hydraulic properties of heterogeneous and complex aquifers often requires field scale investigations at multiple space and time scales to better constrain hydraulic property estimates. Here, we present and discuss results from the site of Ploemeur (Brittany, France) where complementary hydrological and geophysical approaches have been combined to characterize the hydrogeological functioning of this highly fractured crystalline rock aquifer. In particular, we show how cross-borehole flowmeter tests, pumping tests and frequency domain analysis of groundwater levels allow quantifying the hydraulic properties of the aquifer at different scales. In complement, we used groundwater temperature as an excellent tracer for characterizing groundwater flow. At the site scale, measurements of ground surface deformation through long-base tiltmeters provide robust estimates of aquifer storage and allow identifying the active structures where groundwater pressure changes occur, including those acting during recharge process. Finally, a numerical model of the site that combines hydraulic data and groundwater ages confirms the geometry of this complex aquifer and the consistency of the different datasets. The Ploemeur site, which has been used for water supply at a rate of about 106 m3 per year since 1991, belongs to the French network of hydrogeological sites H+ and is currently used for monitoring groundwater changes and testing innovative field methods.
AGU Fall Meeting 2014
San Francisco, United States

insu-01088596
https://hal-insu.archives-ouvertes.fr/insu-01088596

Éditeur(s) : HAL CCSD Geological Society of London
Résumé : This paper presents the background for the calculation of physical properties of an aggregate from constituent crystal properties and the texture of the aggregate in a coherent manner. Emphasis is placed on the important tensor properties of 2nd and 4th rank with applications in rock deformation, structural geology, geodynamics and geophysics. We cover texture information that comes from pole figure diffraction and single orientation measurements (electron backscattered diffraction or EBSD, electron channelling pattern, Laue pattern, optical microscope universal-stage). In particular, we provide explicit formulae for the calculation of the averaged tensor from individual orientations or from an orientation distribution function (ODF). For the latter we consider numerical integration and an approach based on the expansion into spherical harmonics. This paper also serves as a reference paper for the mathematical tensor capabilities of the texture analysis software MTEX, which is a comprehensive, freely available MatLab toolbox that covers a wide range of problems in quantitative texture analysis, for example, ODF modelling, pole figure to ODF inversion, EBSD data analysis and grain detection. MTEX offers a programming interface which allows the processing of involved research problems as well as highly customizable visualization capabilities; MTEX is therefore ideal for presentations, publications and teaching demonstrations.
Deformation Mechanisms, Rheology and Tectonics: Microstructures, Mechanics and Anisotropy

hal-00688833
https://hal.archives-ouvertes.fr/hal-00688833

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Fault friction is a parameter that is difficult to assess along fault zones since its determination depends on the knowledge of any factor controlling the state of stress around faults. In brittle homogeneous rocks, a limited number of these factors, such as the shape of the fault surface, the vicinity of fault tips or the remote stress ratio, are crucial to constrain for this determination. In this paper, we propose to analyse a field example in which all these properties are met and where the nature of the slipped structure suggest differences in static friction. We compare the orientations of branching fractures at strike-slip relay zones between en echelon stylolites and en echelon joints both reactivated in shear. The field data are compared with both photoelastic and 3-D numerical models that consider the remote stress conditions and the role of the geometry of the strike-slip segments. Based on field observations, these analyses quantitatively demonstrate the significant role of fault friction on the local stress field orientation and subsequent fracture formation. This work points out that estimations of fault friction based on analyses of fracture patterns or in situ stresses must be accompanied with a thorough investigation of the 3-D fault shape, its segmentation and the remote stress state.
ISSN: 0191-8141

hal-00560999
https://hal.archives-ouvertes.fr/hal-00560999
DOI : 10.1016/j.jsg.2010.01.008

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
We derive a general formulation of the time domain random walk (TDRW) approach to model the hydrodynamic transport of inert solutes in complex geometries and heterogeneous media. We demonstrate its formal equivalence with the discretized advection-dispersion equation and show that the TDRW is equivalent to a continuous time random walk (CTRW) characterized by space-dependent transition times and transition probabilities. The transition times are exponentially distributed. We discuss the implementation of different concentration boundary conditions and initial conditions as well as the occurrence of numerical dispersion. Furthermore, we propose an extension of the TDRW scheme to account for mobile-immobile multirate mass transfer. Finally, the proposed TDRW scheme is validated by comparison to analytical solutions for spatially homogeneous and heterogeneous transport scenarios.
ISSN: 0043-1397

hal-01356319
https://hal.archives-ouvertes.fr/hal-01356319
DOI : 10.1002/2015WR018511

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Electrical resistivity soundings are used by geophysicists to determine the structure and composition of the Earth's crust and mantle and to explore natural resources (ore, oil, gas, water). Their interpretations in terms of composition and in-situ physical conditions depend mainly on laboratory measurements of electrical conductivity of rocks at simulated crustal conditions of temperature, pressure, saturation and pore pressures. These measurements present a numbers of limitations, in particular, in the case where conductive pore fluids are present, as in the case of deep reservoir conditions, where temperature exceeds 250 A degrees C. Here, we present a new cell capable of measuring electrical conductivity of large saturated samples at confining pressure up to 200 MPa, pore pressure up to 50 MPa, and temperature up to 500 A degrees C. The measurement cell has been developed in a commercial, internally heated, gas pressure apparatus (Paterson press). It is based on the concept of "guard ring" electrode, which is adapted to samples that are jacketed by a very conductive, metallic material. Numerical modeling of the current flow in the electrical cell allowed defining the optimal cell geometry. Calibration tests have been performed on Fontainebleau sandstones saturated with electrolytes of different conductivities, up to 350 A degrees C. The resulting electrical formation factor and temperature dependence of electrical conductivity are in very good agreement with previous studies. This new cell will improve the exploration and exploitation of deep fluid reservoirs, as in unconventional, high enthalpy geothermal fields. In particular, the investigations address possible effects of fluid-rock interactions on electrical resistivity of a reservoir host rock.
ISSN: 0169-3913

hal-00681997
https://hal.archives-ouvertes.fr/hal-00681997
DOI : 10.1007/s11242-011-9846-2