Inferring field‐scale properties of a fractured aquifer from ground surface deformation during a well test

Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Boudin, F.; Durand, Stéphane; Lavenant, Nicolas

doi:10.1002/2015gl066387

Cited by 21 publications

(32 citation statements)

References 32 publications

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“…The orientation of the horizontal strain axes associated with IC2 (Figure ) suggests that this hydrological forcing acts on existing rock fractures and the signal is amplified in karst terrains. At a local scale, water infiltration and associated pressure change was proposed to explain tilt and surface deformation signals in fractured outcrops (e.g., Devoti et al, ; Jacob et al, ; Longuevergne et al, ; Schuite et al, ). Important water level changes (of the order of tens of meters) are common in karst environments (Milanović, , ), where narrow fractures can drain water from large areas, focusing the effects of pressure changes within thin, subvertical structures.…”

Section: Interpreting the Link Between Precipitation And Deformationmentioning

confidence: 99%

Hydrologically Induced Karst Deformation: Insights From GPS Measurements in the Adria‐Eurasia Plate Boundary Zone

et al. 2018

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We apply a blind source separation algorithm to the ground displacement time series recorded at continuous Global Positioning System (GPS) stations in the European Eastern Alps and Northern Dinarides. As a result, we characterize the temporal and spatial features of several deformation signals. Seasonal displacements are well described by loading effects caused by Earth surface mass redistributions. More interestingly, we highlight a horizontal, nonseasonal, transient deformation signal, with spatially variable amplitudes and directions. The stations affected by this signal reverse the sense of movement with time, implying a sequence of dilatational and compressional deformation that is oriented normal to rock fractures in karst areas. The temporal evolution of this deformation signal is correlated with the history of cumulated precipitations at monthly time scales. This transient horizontal deformation can be explained by pressure changes associated with variable water levels within vertical fractures in the vadose zones of karst systems. The water level changes required to open or close these fractures are consistent with the fluctuations of precipitation and with the dynamics of karst systems.

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Section: Interpreting the Link Between Precipitation And Deformationmentioning

confidence: 99%

Hydrologically Induced Karst Deformation: Insights From GPS Measurements in the Adria‐Eurasia Plate Boundary Zone

et al. 2018

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“…As the fracture's aperture increases with pressure and given the validity of the cubic law, the flow field might not only be modified, but the stationarity of properties such as transmissivity T h and storativity S, which depend on the fracture's mechanical state (aperture a and normal stiffness k n ), might be questioned as discussed by Manga et al [2012], Murdoch and Germanovich [2012], Shapiro and Hsieh [1998], and Wang and Cardenas, [2016]. Finally, monitoring reservoir deformation and fluid pressure changes has been proven useful to identify the geometry and estimate HM properties of hydraulically active structures at different scales [Cappa et al, 2006b;Evans and Wyatt, 1984;Rutqvist, 2015;Schuite et al, 2015].…”

Section: Introductionmentioning

confidence: 99%

Combining periodic hydraulic tests and surface tilt measurements to explore in situ fracture hydromechanics

et al. 2017

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Fractured bedrock reservoirs are of socio‐economical importance, as they may be used for storage or retrieval of fluids and energy. In particular, the hydromechanical behavior of fractures needs to be understood as it has implications on flow and governs stability issues (e.g., microseismicity). Laboratory, numerical, or field experiments have brought considerable insights to this topic. Nevertheless, in situ hydromechanical experiments are relatively uncommon, mainly because of technical and instrumental limitations. Here we present the early stage development and validation of a novel approach aiming at capturing the integrated hydromechanical behavior of natural fractures. It combines the use of surface tiltmeters to monitor the deformation associated with the periodic pressurization of fractures at depth in crystalline rocks. Periodic injection and withdrawal advantageously avoids mobilizing or extracting significant amounts of fluid, and it hinders any risk of reservoir failure. The oscillatory perturbation is intended to (1) facilitate the recognition of its signature in tilt measurements and (2) vary the hydraulic penetration depth in order to sample different volumes of the fractured bedrock around the inlet and thereby assess scale effects typical of fractured systems. By stacking tilt signals, we managed to recover small tilt amplitudes associated with pressure‐derived fracture deformation. Therewith, we distinguish differences in mechanical properties between the three tested fractures, but we show that tilt amplitudes are weakly dependent on pressure penetration depth. Using an elastic model, we obtain fracture stiffness estimates that are consistent with published data. Our results should encourage further improvement of the method.

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“…(b) Electrical resistivity values (ρ) interpreted from ERT carried out along the W-E line. Five main structures are delineated: fresh granite (FG), weathered granite (WG), micaschists (MS) overlaid by clays (CL) and the contact zone (hashed area) due to a fault network striking N20°(Touchard 1999;Schuite et al 2015).…”

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confidence: 99%

Estimating picking errors in near‐surface seismic data to enable their time‐lapse interpretation of hydrosystems

Dangeard

Bodet

Pasquet

et al. 2018

Near Surface Geophysics

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Time‐lapse applications of seismic methods have been recently suggested in the near‐surface scale to track hydrological properties variations due to climate, water level changes, or permafrost thaw, for instance. But when it comes to traveltime tomography or surface‐wave dispersion inversion, a careful estimation of the data variability associated with the picking process must be considered prior to any time‐lapse interpretation. In this study, we propose to estimate picking errors that are due to the inherent subjectivity of human operators, using statistical analysis based on picking repeatability. Two seismic datasets were collected along the same profile under distinct hydrological conditions across a granite–micaschist contact at the Ploemeur hydrological observatory (France). Both datasets were recorded using identical equipment and acquisition parameters. A thorough statistical analysis is conducted to estimate picking uncertainties, at the 99% confidence level, for both P‐wave first arrival time and surface‐wave phase velocity. With the suggested workflow, we are able to identify 33% of the P‐wave traveltimes and 16% of the surface‐wave dispersion data, which can be considered significant enough for time‐lapse interpretations. In this selected portion of the data, point‐by‐point differences highlight important variations linked to different hydrogeological properties of the subsurface. These variations show strong contrasts with a non‐monotonous behaviour along the line, offering new insights to better constrain the dynamics of this hydrosystem.

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Inferring field‐scale properties of a fractured aquifer from ground surface deformation during a well test

Cited by 21 publications

References 32 publications

Hydrologically Induced Karst Deformation: Insights From GPS Measurements in the Adria‐Eurasia Plate Boundary Zone

Hydrologically Induced Karst Deformation: Insights From GPS Measurements in the Adria‐Eurasia Plate Boundary Zone

Combining periodic hydraulic tests and surface tilt measurements to explore in situ fracture hydromechanics

Estimating picking errors in near‐surface seismic data to enable their time‐lapse interpretation of hydrosystems

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