Data processing for oscillatory pumping tests

Bakhos, Tania; Cardiff, Michael; Barrash, Warren; Kitanidis, Peter K.

doi:10.1016/j.jhydrol.2014.01.007

Cited by 38 publications

(63 citation statements)

References 33 publications

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“…In future work, we would like to perform more detailed comparisons between OHT and other suggested hydraulic tomography characterization strategies, including transient hydraulic tomography (THT) inversion of data from constant-rate pumping tests, and travel time/amplitude inversion of data from slug testing [e.g., Brauchler et al, 2007]. Additional investigation is also necessary to determine why our inversions exhibited poor convergence if the theoretically correct data error magnitudes (following Bakhos et al [2014]) were used for inverting multifrequency data. A best practice for future investigations may be to utilize Water Resources Research 10.1002/2015WR017751 restricted maximum likelihood techniques [Kitanidis, 1995] to automatically determine data weights at different periods, a method which can be investigated using the dataset presented here.…”

Section: Discussionmentioning

confidence: 99%

Aquifer imaging with pressure waves—Evaluation of low‐impact characterization through sandbox experiments

Zhou

Lim

Cupola

et al. 2016

Water Resources Research

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Understanding the detailed spatial variation of hydraulic properties in the subsurface has been the subject of intensive research over the past three decades. A recently developed approach to characterize subsurface properties is hydraulic tomography, in which a series of pumping tests are jointly inverted using a heterogeneous numerical model. Recently, Cardiff et al. (2013) proposed a modified tomography approach named Oscillatory Hydraulic Tomography (OHT), in which periodic pumping signals of different frequencies serve as the aquifer stimulation, and pressure responses are recorded at observation locations for tomographic analysis. Its key advantages over traditional hydraulic tomography are that: (1) there is no net injection or extraction of water, and (2) the impulse (an oscillatory signal of known frequency) is easily extracted from noisy data. However, OHT has only been evaluated through numerical experiments to date. In this work, we evaluate OHT performance by attempting to image known heterogeneities in a synthetic aquifer. An instrumented laboratory sandbox is filled with material of known hydraulic properties, and we measure aquifer responses due to oscillatory pumping stimulations at periods of 2, 5, 10, and 20 s. Pressure oscillation time series are processed through Fourier Transforms and inverted tomographically to obtain estimates of aquifer heterogeneity, using a fast, steady‐periodic groundwater flow model. We show that OHT is able to provide robust estimates of aquifer hydraulic conductivity even in cases where relatively few pumping tests and observation locations are available. The use of multiple stimulation frequencies is also shown to improve imaging results.

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Section: Discussionmentioning

confidence: 99%

Aquifer imaging with pressure waves—Evaluation of low‐impact characterization through sandbox experiments

Zhou

Lim

Cupola

et al. 2016

Water Resources Research

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“…Bakhos et al . [] presented a least squares based technique to filter the sinusoidal signal associated with harmonic pumping tests and performed the joint inversion of storativity and hydraulic conductivity using HHT. Rabinovich et al .…”

Section: Introductionmentioning

confidence: 99%

“…Cardiff et al [2013] performed sensitivity analysis for multiple frequencies harmonic pumping tests and estimated the hydraulic conductivity of a synthetic aquifer using HHT combined with the geostatistical framework of Kitanidis [1995Kitanidis [ , 1996. Bakhos et al [2014] presented a least squares based technique to filter the sinusoidal signal associated with harmonic pumping tests and performed the joint inversion of storativity and hydraulic conductivity using HHT. Rabinovich et al [2015] used harmonic pumping tests to estimate the effective storativity, specific yield, and hydraulic conductivity of the Boise Hydrogeophysical Research Site in USA.…”

Section: Introductionmentioning

confidence: 99%

Joint inversion of hydraulic head and self‐potential data associated with harmonic pumping tests

Ahmed

Jardani

Revil

et al. 2016

Water Resources Research

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Harmonic pumping tests consist in stimulating an aquifer by the means of hydraulic stimulations at some discrete frequencies. The inverse problem consisting in retrieving the hydraulic properties is inherently ill posed and is usually underdetermined when considering the number of well head data available in field conditions. To better constrain this inverse problem, we add self‐potential data recorded at the ground surface to the head data. The self‐potential method is a passive geophysical method. Its signals are generated by the groundwater flow through an electrokinetic coupling. We showed using a 3‐D saturated unconfined synthetic aquifer that the self‐potential method significantly improves the results of the harmonic hydraulic tomography. The hydroelectric forward problem is obtained by solving first the Richards equation, describing the groundwater flow, and then using the result in an electrical Poisson equation describing the self‐potential problem. The joint inversion problem is solved using a reduction model based on the principal component geostatistical approach. In this method, the large prior covariance matrix is truncated and replaced by its low‐rank approximation, allowing thus for notable computational time and storage savings. Three test cases are studied, to assess the validity of our approach. In the first test, we show that when the number of harmonic stimulations is low, combining the harmonic hydraulic and self‐potential data does not improve the inversion results. In the second test where enough harmonic stimulations are performed, a significant improvement of the hydraulic parameters is observed. In the last synthetic test, we show that the electrical conductivity field required to invert the self‐potential data can be determined with enough accuracy using an electrical resistivity tomography survey using the same electrodes configuration as used for the self‐potential investigation.

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“…In addition, modeling of periodic tests can be performed in the frequency domain, allowing faster simulations than are possible with typical transient numerical models (e.g., Townley ; Cardiff et al ). Periodic pumping tests also have several practical benefits for field implementation, especially in cases where the oscillatory pumping is “zero‐mean,” that is, the pumping strategy consists of alternating periods of injection and extraction, so that no net drawdown is caused: Oscillating signals of known frequency are easily separated from sensor noise and drift, and from other over‐printed hydrologic processes by using Fourier‐domain signal processing routines (Bakhos et al ). Zero‐mean periodic pumping tests may help to avoid costs and risks associated with handling and treating significant amounts of contaminated water, relative to traditional pumping tests. Zero‐mean periodic pumping tests of reasonable amplitudes should not cause significant contaminant plume movement, relative to traditional pumping tests, since the average flow velocity induced by such pumping is zero in all directions. Periodic testing can be performed at different frequencies to obtain additional information about aquifer heterogeneity (Cardiff et al ). In scenarios where continuous pumping is required (e.g., a pump‐and‐treat capture well), a periodic signal can be over‐printed on the pumping well by periodically varying the pumping rate above and below the desired long‐term rate. …”

Section: Introductionmentioning

confidence: 99%

“…• Oscillating signals of known frequency are easily separated from sensor noise and drift, and from other over-printed hydrologic processes by using Fourierdomain signal processing routines (Bakhos et al 2014). • Zero-mean periodic pumping tests may help to avoid costs and risks associated with handling and treating significant amounts of contaminated water, relative to traditional pumping tests.…”

Section: Introductionmentioning

confidence: 99%

Analytical and Semi‐Analytical Tools for the Design of Oscillatory Pumping Tests

Cardiff¹,

Barrash

2014

Groundwater

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Oscillatory pumping tests-in which flow is varied in a periodic fashion-provide a method for understanding aquifer heterogeneity that is complementary to strategies such as slug testing and constant-rate pumping tests. During oscillatory testing, pressure data collected at non-pumping wells can be processed to extract metrics, such as signal amplitude and phase lag, from a time series. These metrics are robust against common sensor problems (including drift and noise) and have been shown to provide information about aquifer heterogeneity. Field implementations of oscillatory pumping tests for characterization, however, are not common and thus there are few guidelines for their design and implementation. Here, we use available analytical solutions from the literature to develop design guidelines for oscillatory pumping tests, while considering practical field constraints. We present two key analytical results for design and analysis of oscillatory pumping tests. First, we provide methods for choosing testing frequencies and flow rates which maximize the signal amplitude that can be expected at a distance from an oscillating pumping well, given design constraints such as maximum/minimum oscillator frequency and maximum volume cycled. Preliminary data from field testing helps to validate the methodology. Second, we develop a semi-analytical method for computing the sensitivity of oscillatory signals to spatially distributed aquifer flow parameters. This method can be quickly applied to understand the "sensed" extent of an aquifer at a given testing frequency. Both results can be applied given only bulk aquifer parameter estimates, and can help to optimize design of oscillatory pumping test campaigns.

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Data processing for oscillatory pumping tests

Cited by 38 publications

References 33 publications

Aquifer imaging with pressure waves—Evaluation of low‐impact characterization through sandbox experiments

Aquifer imaging with pressure waves—Evaluation of low‐impact characterization through sandbox experiments

Joint inversion of hydraulic head and self‐potential data associated with harmonic pumping tests

Analytical and Semi‐Analytical Tools for the Design of Oscillatory Pumping Tests

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