Hydromechanical behavior during constant-rate pumping tests in fractured gneiss

Schweisinger, Todd; Svenson, Erik; Murdoch, Lawrence C.

doi:10.1007/s10040-011-0728-z

Cited by 22 publications

(34 citation statements)

References 36 publications

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“…They appear strongest in the open borehole house wells and weakest in the cased and screened monitoring wells. This behavior is similar to that observed by Schweisinger et al () during pumping tests in fractured gneiss. In that study, drawdown during pumping tests varied depending on whether the borehole was open or packed off to isolate fractured intervals.…”

Section: Methods and Resultssupporting

confidence: 91%

Reverse Water‐Level Fluctuations Associated with Fracture Connectivity

et al. 2013

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Reverse water-level fluctuations (RWFs), a phenomenon in which water levels rise briefly in response to pumping, were detected in monitoring wells in a fractured siliciclastic aquifer system near a deep public supply well. The magnitude and timing of RWFs provide important information that can help interpret aquifer hydraulics near pumping wells. A RWF in a well is normally attributed to poroelastic coupling between the solid and fluid components in an aquifer system. In addition to revealing classical pumping-induced poroelastic RWFs, data from pressure transducers located at varying depths and distances from the public supply well suggest that the RWFs propagate rapidly through fractures to influence wells hundreds of meters from the pumping well. The rate and cycling frequency of pumping is an important factor in the magnitude of RWFs. The pattern of RWF propagation can be used to better define fracture connectivity in an aquifer system. Rapid, cyclic head changes due to RWFs may also serve as a mechanism for contaminant transport.

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Section: Methods and Resultssupporting

confidence: 91%

Reverse Water‐Level Fluctuations Associated with Fracture Connectivity

et al. 2013

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“…This was accomplished using the parameter estimation software PEST, a model‐independent program that utilizes the Gauss‐Marquardt‐Levenberg method to minimize an objective function using nonlinear regression [ Waterloo Hydrogeologic , Inc ., ]. A similar approach was used to analyze hydromechanical slug test data from this site [ Svenson , ; Svenson et al ., ; Schweisinger et al ., ]. Previous work was limited to data sets obtained from the test well, so they did not include signals with an RWC.…”

Section: Numerical Analysismentioning

confidence: 99%

Reverse water‐level change during interference slug tests in fractured rock

Slack

Murdoch

Germanovich

et al. 2013

Water Resources Research

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[1] Reverse water-level responses in monitoring wells are widely known during pumping tests, where they are recognized as the Noordbergum or Rhade effects, and a similar response was observed in many of the 100þ interference slug tests conducted at a well field near Clemson, South Carolina. The reverse water-level effect is characterized by a drop in pressure head by 1 cm to several centimeters and it occurs in the first 10-100 s of the test. The reverse response is followed by a rise and fall of pressure head that is typical of slug-in tests. The reverse water-level response is highly repeatable, and it increases when the pressure used to create the slug test is increased. A conceptual model recognizes that opening displacement of the fracture wall can cause a pressure drop, even when the pressure increases in the wellbore. The conceptual model is supported by a closed-form, analytical solution and a numerical model that couple fluid pressure and deformation in a fracture. Characteristics of the reverse water-level response are sensitive to properties of the fracture system and enveloping formation. Parameter estimation methods can be used to invert theoretical analyses and use the reverse response to improve the characterization of fractured rock aquifers.

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“…It is plausible that even slight changes in water pressure may affect fracture aperture and well testing results, analogous to the changes observed during hydro‐fracturing. There are few attempts to evaluate the hydromechanical response of a fractured rock to a slight change in water pressure (Cappa et al 2006; Svenson et al 2008; Schweisinger et al 2011). They installed the extensometers in a packed‐off section of boreholes in highly fractured rock aquifers, and measured the axial displacements and pressures during various well tests such as slug, pulse, and pumping tests.…”

Section: Introductionmentioning

confidence: 99%

Influence of Pressure Change During Hydraulic Tests on Fracture Aperture

Ji¹,

Koh

Kuhlman

et al. 2012

Groundwater

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In a series of field experiments, we evaluate the influence of a small water pressure change on fracture aperture during a hydraulic test. An experimental borehole is instrumented at the Korea Atomic Energy Research Institute (KAERI) Underground Research Tunnel (KURT). The target fracture for testing was found from the analyses of borehole logging and hydraulic tests. A double packer system was developed and installed in the test borehole to directly observe the aperture change due to water pressure change. Using this packer system, both aperture and flow rate are directly observed under various water pressures. Results indicate a slight change in fracture hydraulic head leads to an observable change in aperture. This suggests that aperture change should be considered when analyzing hydraulic test data from a sparsely fractured rock aquifer.

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Hydromechanical behavior during constant-rate pumping tests in fractured gneiss

Cited by 22 publications

References 36 publications

Reverse Water‐Level Fluctuations Associated with Fracture Connectivity

Reverse Water‐Level Fluctuations Associated with Fracture Connectivity

Reverse water‐level change during interference slug tests in fractured rock

Influence of Pressure Change During Hydraulic Tests on Fracture Aperture

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