Comparison of travel-time and geostatistical inversion approaches for hydraulic tomography: A synthetic modeling study

Travel time based hydraulic tomography is a technique for reconstructing the spatial distribution of aquifer hydraulic properties (e.g., hydraulic diffusivity). Simultaneous Iterative Reconstruction Technique (SIRT) is a widely used algorithm for travel time related inversions. Due to the drawbacks of SIRT implementation in practice, a modified SIRT with Cimmino iteration (SIRT-Cimmino) is proposed in this study. The incremental correction is adjusted, and an iteration-dependent relaxation parameter is introduced. These two modifications enable an appropriate speed of convergence, and the stability of the inversion process. Furthermore, a new result selection rule is suggested to determine the optimal iteration step and its corresponding result. SIRT-Cimmino and SIRT are implemented and verified by using two numerical aquifer models with different predefined (“true”) diffusivity distributions, where high diffusivity zones are embedded in a homogenous low diffusivity field. Visual comparison of the reconstructions shows that the reconstruction based on SIRT-Cimmino demonstrates the aquifer’s hydraulic features better than the conventional SIRT algorithm. Root mean square errors and correlation coefficients are also used to quantitatively evaluate the performance of the inversion. The reconstructions based on SIRT-Cimmino are found to preserve the connectivity of the high diffusivity zones and to provide a higher structural similarity to the “true” distribution.

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Reconstruction of P-Wave Velocity Model through Geostatistical Inversion of Seismic Travel Time for Offshore Site Characterization

10.3997/2214-4609.202020029 ◽

2020 ◽

Author(s):

M. Moradi ◽

Z. Medina-Cetina

Keyword(s):

Travel Time ◽

Wave Velocity ◽

Velocity Model ◽

Site Characterization ◽

P Wave ◽

P Wave Velocity ◽

Geostatistical Inversion

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Vibroseis recording techniques and data reduction from the Jemez Tomography Experiment

Bulletin of the Seismological Society of America ◽

10.1785/bssa0890051352 ◽

1999 ◽

Vol 89 (5) ◽

pp. 1352-1365

Author(s):

Mark E. Davidson ◽

Lawrence W. Braile

Keyword(s):

Travel Time ◽

High Signal ◽

Volcanic System ◽

Reflection Seismic ◽

Multidisciplinary Study ◽

Crustal Model ◽

Source Data ◽

Silicic Volcanic ◽

Seismograph Station ◽

Synthetic Modeling

Abstract The Jemez Tomography Experiment (JTEX) is a multidisciplinary study focused on the Valles Caldera and the Jemez Mountains, New Mexico. The objectives of the project are to create a high resolution crustal model of the subsurface structure of this silicic volcanic system and to develop an interpretation of its volcanic evolution. Use of Vibroseis sources in the acquisition of refraction/wide-angle reflection seismic data provided challenges beyond conventional explosive-source data. Processing of the JTEX Vibroseis data is an involved procedure consisting of sorting, cross-correlating, filtering, and stacking numerous individual seismograms in the production of final record sections. However, excellent results (high signal-to-noise seismograms at relatively small spacings) are obtainable with coherent arrivals at source-receiver distances of more than 60 km. The primary drawback in this approach lies in the massive volume of data that is necessary to produce record sections. One benefit of the Vibroseis source used during JTEX was a method to decrease effective seismogram spacing. This technique, dubbed a “source-offset” technique, provides smaller overall seismograph station spacing by moving the Vibroseis sources during acquisition and leaving deployed seismographs stationary. After station corrections, this method effectively decreases station spacings and increases detail in resulting record sections. Various shallow crustal heterogeneities create travel-time advances and delays that affect the source-offset data differently than single-source data. Synthetic modeling demonstrates small travel-time discrepancies associated with the source-offset technique. However, the addition of traces with smaller station intervals clarifies secondary arrivals within record sections and aids in interpretation of these arrivals with a minimum amount of field effort required.

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Hydraulic tomography analog outcrop study: Combining travel time and steady shape inversion

Journal of Hydrology ◽

10.1016/j.jhydrol.2011.08.031 ◽

2011 ◽

Vol 409 (1-2) ◽

pp. 350-362 ◽

Cited By ~ 32

Author(s):

R. Hu ◽

R. Brauchler ◽

M. Herold ◽

P. Bayer

Keyword(s):

Travel Time ◽

Hydraulic Tomography

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Combination of Hydraulic and Thermal Tracer Tomography in a Heterogeneous Transient Groundwater Model

10.5194/egusphere-egu2020-21266 ◽

2020 ◽

Author(s):

Junjie Qi ◽

Rui Hu ◽

Quan Liu ◽

Linwei Hu ◽

Thomas Ptak

Keyword(s):

Hydraulic Conductivity ◽

Travel Time ◽

Hot Water ◽

Water Model ◽

Detailed Knowledge ◽

Groundwater Model ◽

Specific Storage ◽

Data Set ◽

Hydraulic Tomography ◽

Subsurface Investigation

Abstract: In recent years, more and more attention has been paid to engineering projects, such as the remediation of contaminated groundwater, the restoration of water quality, and the seepage control of building foundations. For all these projects, detailed knowledge of the spatial distribution of aquifer hydraulic parameters is required. Inversion based tomography can be considered a promising subsurface investigation approach to obtain aquifer characterization with a high spatial resolution. However, single inversion cannot avoid parameter uncertainty and non-uniqueness problems. Combination of different independent inversions can help to reduce these problems. The purpose of this paper is to reconstruct cross-well hydraulic conductivity profiles by jointly using hydraulic tomography and thermal tracer tomography in a heterogeneous transient groundwater model.In this study, based on a three-dimensional data set derived from an aquifer analogue outcrop study, a numerical ground water model is set up to simulate a number of short-term hot water injection tests in a tomographical array, and to perform 2D hydraulic tomography based on hydraulic travel time and attenuation inversions. Consequently, the hydraulic conductivity is calculated from the obtained diffusivity and specific storage values. Parallel to this, the temperature breakthrough curves of the active thermal tracers were utilized to reconstruct the cross-well hydraulic conductivity profiles by using travel-time-based thermal tracer tomography. Comparisons between the results and the &#8220;true values&#8221; of the analog have shown the satisfying accuracy of the subsurface investigation and advantages when using combined tomographical methods.

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Detection of karst conduit patterns via hydraulic tomography: A synthetic inverse modeling study

Journal of Hydrology ◽

10.1016/j.jhydrol.2019.02.044 ◽

2019 ◽

Vol 572 ◽

pp. 131-147 ◽

Cited By ~ 3

Author(s):

Zargham Mohammadi ◽

Walter A. Illman

Keyword(s):

Inverse Modeling ◽

Hydraulic Tomography ◽

Karst Conduit ◽

Modeling Study

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Application of Wavelet De-Noising for Travel-Time Based Hydraulic Tomography

Water ◽

10.3390/w12061533 ◽

2020 ◽

Vol 12 (6) ◽

pp. 1533

Author(s):

Huichen Yang ◽

Rui Hu ◽

Pengxiang Qiu ◽

Quan Liu ◽

Yixuan Xing ◽

...

Keyword(s):

Experimental Data ◽

Data Processing ◽

Travel Time ◽

Gaussian White Noise ◽

Test Site ◽

Pumping Test ◽

Time Inversion ◽

Fractured Aquifer ◽

Hydraulic Tomography ◽

Travel Time Inversion

Travel-time based hydraulic tomography is a promising method to characterize heterogeneity of porous-fractured aquifers. However, there is inevitable noise in field-scale experimental data and many hydraulic signal travel times, which are derived from the pumping test’s first groundwater level derivative drawdown curves and are strongly influenced by noise. The required data processing is thus quite time consuming and often not accurate enough. Therefore, an effective and accurate de-noising method is required for travel time inversion data processing. In this study, a series of hydraulic tomography experiments were conducted at a porous-fractured aquifer test site in Goettingen, Germany. A numerical model was built according to the site’s field conditions and tested based on diagnostic curve analyses of the field experimental data. Gaussian white noise was then added to the model’s calculated pumping test drawdown data to simulate the real noise in the field. Afterward, different de-noising methods were applied to remove it. This study has proven the superiority of the wavelet de-noising approach compared with several other filters. A wavelet de-noising method with calibrated mother wavelet type, de-noising level, and wavelet level was then determined to obtain the most accurate travel time values. Finally, using this most suitable de-noising method, the experimental hydraulic tomography travel time values were calculated from the de-noised data. The travel time inversion based on this de-noised data has shown results consistent with previous work at the test site.

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An inversion strategy for hydraulic tomography: Coupling travel time and amplitude inversion

Journal of Hydrology ◽

10.1016/j.jhydrol.2007.08.011 ◽

2007 ◽

Vol 345 (3-4) ◽

pp. 184-198 ◽

Cited By ~ 34

Author(s):

R. Brauchler ◽

J.-T. Cheng ◽

P. Dietrich ◽

M. Everett ◽

B. Johnson ◽

...

Keyword(s):

Travel Time ◽

Hydraulic Tomography ◽

Amplitude Inversion

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Stochastic Modeling of Diffusivity and Constant-Rate Pumping Tests in Heterogeneous Aquifers in a Tomographic Setup and Its Application to Field Measurements

10.5194/egusphere-egu21-2680 ◽

2021 ◽

Author(s):

Kan Bun Cheng ◽

Gedeon Dagan ◽

Avinoam Rabinovich

Keyword(s):

Hydraulic Conductivity ◽

Travel Time ◽

Field Measurements ◽

Specific Storage ◽

First Order ◽

Hydraulic Tomography ◽

Constant Rate ◽

Mean And Variance ◽

The Mean ◽

Aquifer Properties

Characterization of spatially variable aquifer properties is a necessary first step towards modeling flow and transport. An emerging technique in hydraulic tomography, known as diffusivity tests, consist of injecting (or pumping) a volume of water through short segments of a well for a short time and measuring the travel time of the peak of the head signal at different points in the surrounding aquifer volume. In our stochastic model, the specific storage is assumed to be constant, while the hydraulic conductivity of the heterogeneous aquifer is modeled as a random lognormal field. The axi-symmetric anisotropic structure is characterized by a few parameters (logconductivity mean and variance and horizontal and vertical integral scales). The mean and variance of the peak travel time are then determined as a function of distance from an instantaneous source by solving the flow equation using a first-order approximation in the logconductivity variance. The mean travel time is recast in terms of the equivalent conductivity, which decreases from the harmonic mean near the source to the effective conductivity in uniform flow for a sufficiently large distance. Similarly, the variance drops from its maximum near the source to a small value.A different type of tomographic test is the constant-rate pumping one. We propose to apply the first order stochastic approach to the data from the Boise Hydrogeophysical Research site (BHRS) to characterize the aquifer properties by estimating heterogeneity statistical parameters. Equivalent properties are first calculated by matching a homogeneous aquifer solution to the pointwise data to obtain a spatially varying hydraulic conductivity (Keq) and storativity (Ss,eq). Then the statistical properties of K and Ss are to be computed by a best fit between the theoretically derived statistical moments of the equivalent random properties (Keq, Ss,eq) and those from field measurements. Our preliminary results indicate that the proposed stochastic methodology is robust and reliable as well as computationally more efficient than the conventional hydraulic tomography techniques.

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