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Outremont, Canada

Roy J.,IGP | Lubczynski M.W.,University of Twente
Near Surface Geophysics | Year: 2014

Several magnetic resonance soundings (MRS) in the Netherlands showed a monotonous single peak anomaly on the amplitude versus excitation moment sounding pattern, which were interpreted as a single aquifer when using an amplitude-only mode MRS data inversion. However, in all these soundings, borehole logs documented the presence of two or three aquifers separated by clay-rich aquitards in the first 100 m below ground surface. Such environments were electrically conductive so a phase excursion was noticeable on the MRS soundings. Multi-aquifer systems, in a conductive environment, may show interference among signals originating from different parts of the systems including amplitude masking or destructive interference. A new version of an off-the-shelf MRS forward modelling and inversion tool (Samovar 11.3) allowing complex amplitude and phase inversion was used to detect and parameterize deep, MRS-masked second aquifers at two selected sites in the Netherlands, one near Delft and one near Waalwijk. At the Delft site, the proposed strategy was effective in the detection and characterization of a second previously missed aquifer at 45 m below ground surface, while at the Waalwijk site, the second aquifer was not detected because of a considerably deeper aquifer at 85 m and too small excitation (6000 A ms). However, forward modelling showed that with a larger excitation moment (e.g., 13 000 A ms), detection and parameterization of the second aquifer would become possible when using both amplitude and phase. © 2014 European Association of Geoscientists & Engineers. Source

Frances A.P.,University of Twente | Lubczynski M.W.,University of Twente | Roy J.,IGP | Santos F.A.M.,University of Lisbon | Mahmoudzadeh Ardekani M.R.,Royal Military Academy
Journal of Applied Geophysics | Year: 2014

Hard rock aquifers are highly heterogeneous and hydrogeologically complex. To contribute to the design of hydrogeological conceptual models of hard rock aquifers, we propose a multi-techniques methodology based on a downward approach that combines remote sensing (RS), non-invasive hydrogeophysics and hydrogeological field data acquisition. The proposed methodology is particularly suitable for data scarce areas. It was applied in the pilot research area of Sardón catchment (80km2) located west of Salamanca (Spain). The area was selected because of hard-rock hydrogeology, semi-arid climate and scarcity of groundwater resources.The proposed methodology consisted of three main steps. First, we detected the main hydrogeological features at the catchment scale by processing: (i) a high resolution digital terrain model to map lineaments and to outline fault zones; and (ii) high-resolution, multispectral satellite QuickBird and WorldView-2 images to map the outcropping granite. Second, we characterized at the local scale the hydrogeological features identified at step one with: i) ground penetrating radar (GPR) to assess groundwater table depth complementing the available monitoring network data; ii) 2D electric resistivity tomography (ERT) and frequency domain electromagnetic (FDEM) to retrieve the hydrostratigraphy along selected survey transects; iii) magnetic resonance soundings (MRS) to retrieve the hydrostratigraphy and aquifer parameters at the selected survey sites. In the third step, we drilled 5 boreholes (25 to 48. m deep) and performed slug tests to verify the hydrogeophysical interpretation and to calibrate the MRS parameters. Finally, we compiled and integrated all acquired data to define the geometry and parameters of the Sardón aquifer at the catchment scale.In line with a general conceptual model of hard rock aquifers, we identified two main hydrostratigraphic layers: a saprolite layer and a fissured layer. Both layers were intersected and drained by fault zones that control the hydrogeology of the catchment. The spatial discontinuities of the saprolite layer were well defined by RS techniques while subsurface geometry and aquifer parameters by hydrogeophysics. The GPR method was able to detect shallow water table at depth between 1 and 3. m b.g.s. The hydrostratigraphy and parameterization of the fissured layer remained uncertain because ERT and FDEM geophysical methods were quantitatively not conclusive while MRS detectability was restricted by low volumetric water content. The proposed multi-technique methodology integrating cost efficient RS, hydrogeophysics and hydrogeological field investigations allowed us to characterize geometrically and parametrically the Sardón hard rock aquifer system, facilitating the design of hydrogeological conceptual model of the area. © 2014 Elsevier B.V. Source

Baroncini-Turricchia G.,University of Twente | Baroncini-Turricchia G.,University of Salamanca | Frances A.P.,University of Twente | Lubczynski M.W.,University of Twente | And 2 more authors.
Near Surface Geophysics | Year: 2014

Magnetic resonance sounding (MRS) provides quantitative hydrogeological information on hydrostratigraphy and hydraulic parameters of subsurface (e.g., flow and storage property of aquifers) that can be integrated in distributed hydrologic models. The hydraulic parameters are typically obtained by pumping tests. In this study, we propose an MRS integration method based on optimizing MRS estimates of aquifer hydraulic parameters through hydrologic model calibration. The proposed MRS integration method was applied in the 73 km 2 Carrizal Catchment in Spain, characterized by a shallow unconfined aquifer with an unknown aquifer bottom. 12 MRS survey results were inverted with Samovar 11.3, schematized and integrated in the transient, distributed, coupled, hydrologic, MARMITES-MODFLOW model. As the aquifer bottom was unknown, the aquifer was schematized into one unconfined layer of uniform thickness. For that layer, MRS estimators of specific yield and transmissivity/hydraulic conductivity were calculated as weighted averages of the inverted MRS layers. The MRS integration with hydrologic model was carried out by introducing multipliers of specific yield and transmissivity/hydraulic conductivity that were optimized during transient model calibration using 11 time-series piezometric observation points. The optimized multipliers were 1.0 for specific yield and 3.5*10-9 for hydraulic conductivity. These multipliers were used, and can be used in future MRS investigations in the Carrizal Catchment (and/or adjacent area with similar hydrogeological conditions), to convert MRS survey results into aquifer hydraulic parameters. The proposed method of MRS data integration in the hydrologic model of Carrizal Catchment not only allowed us to calibrate the model but also to confirm the functional capability of MRS in quantitative groundwater assessment. Most importantly however, it demonstrated that if pumping tests are not available, the use of MRS integrated in distributed coupled hydrological models, or even in standalone groundwater models, provides a valuable aquifer parameterization alternative. © 2014 European Association of Geoscientists & Engineers. Source

Clemence M.-E.,CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments | Gardin S.,CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments | Bartolini A.,CNRS Center for Research on Palaeobiodiversity and Palaeoenvironments | Paris G.,French Institute of Petroleum | And 2 more authors.
Swiss Journal of Geosciences | Year: 2010

A high-resolution micropalaeontological study, combined with geochemical and sedimentological analyses was performed on the Tiefengraben, Schlossgraben and Eiberg sections (Austrian Alps) in order to characterize sea-surface carbonate production during the end-Triassic crisis. At the end-Rhaetian, the dominant calcareous nannofossil Prinsiosphaera triassica shows a decrease in abundance and size and this is correlated with a increase in δ18O and a gradual decline in δ13Ccarb values. Simultaneously, benthic foraminiferal assemblages show a decrease in diversity and abundance of calcareous taxa and a dominance of infaunal agglutinated taxa. The smaller size of calcareous nannofossils disturbed the vertical export balance of the biological carbon pump towards the sea-bottom, resulting in changes in feeding strategies within the benthic foraminiferal assemblages from deposit feeders to detritus feeders and bacterial scavengers. These micropalaeontological data combined with geochemical proxies suggest that changes in seawater chemistry and/or cooling episodes might have occurred in the latest Triassic, leading to a marked decrease of carbonate production. This in turn culminated in the quasi-absence of calcareous nannofossils and benthic foraminifers in the latest Triassic. The aftermath (latest Triassic earliest Jurassic) was characterised by abundance peaks of "disaster" epifaunal agglutinated foraminifera Trochammina on the sea-floor. Central Atlantic Magmatic Province (CAMP) paroxysmal activity, superimposed on a major worldwide regressive phase, is assumed to be responsible for a deterioration in marine palaeoenvironments. CAMP sulfuric emissions might have been the trigger for cooling episodes and seawater acidification leading to disturbance of the surface carbonate production at the very end-Triassic. © 2010 Swiss Geological Society. Source

Rainaud J.F.,IGP | Verney P.,IGP | Mastella L.,MINES ParisTech
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

We have been claiming for several years that Shared Earth Modeling should be knowledge-driven. This approach considers geology as a key knowledge to which all expert fields necessarily refer. According to this approach, a permanent link can be established at each stage of the modeling process between the various objects considered (seismic reflectors, well markers, geometrical surfaces) and the geological objects (Geological Units, Geologic Boundaries) to which they have been associated thanks to geological interpretation. In this paper we explain how we formalize, populate, reuse, extract and exploit this knowledge for opening the communication between several processing stages (prospect initiation, well marker, seismic interpretation, structural modelling) and for offering the possibility of permanently completing and updating the various representations. This solution, based on a semantic approach, basically consists in formalizing knowledge attached to geological, seismic and well log data by means of Domain Ontologies, operating a knowledge based method for seismic interpretation and providing results allowing automated building of a structural model, opening the possibility of retrieving all useful information concerning the interpretations operated at the various stages of the modeling workflow by means of various knowledge management tools. This solution will be described in reference with a practical example. © 2010, European Association of Geoscientists and Engineers. Source

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