High resolution aquifer characterization using crosshole GPR full-waveform tomography: Comparison with direct-push and tracer test data

<div>Historically, heat and temperature observations have been occasionally used to help understand aquifer systems or constrain numerical flow models. However, the development of fiber optics (FO) as part of the Distributed Temperature Sensing (DTS) technology has spun a renewed interest in the use of heat as a groundwater tracer. Recent studies have shown the possibility to carry out an active heat tracer test using fiber optics and heating cables installed by direct push and to invert the resulting thermal responses to estimate a vertical profile of groundwater fluxes. However, a better understanding of how FO-DTS results compare to other aquifer characterization methods is needed to guide its future application and integration into a practical workflow. The objective of this study was thus to compare the information provided by FO-DTS with other direct and indirect measurements used to characterize the heterogeneity of granular aquifers at multiple scales.&#160;</div><div>The multiscale integrated characterization was carried out at a heterogeneous deltaic aquifer located north of Quebec City, Canada. This aquifer has been the object of a complete hydrogeological characterization and thus provides a wide range of existing data against which the acquired data can be compared. This communication will focus on the multiscale methodology for the granular aquifer characterization including FO-DTS measurements. Based on an existing numerical hydrogeological model, three sites with a range of horizontal groundwater fluxes were selected for active FO-DTS heat tracer experiments. At one of the sites, direct push monitoring wells were also installed downstream to measure the hydraulic conductivity of the hydrofacies and the arrival of the thermal front from the heat tracer test. A previous study established a relationship between the hydrofacies of the deltaic aquifer to cone penetration test (CPT) response. As such, each FO cable and monitoring well direct-push installation was preceded by a co-located CPT. Soil cores were also taken for laboratory measurements of hydraulic and thermal properties.&#160;</div><div>The vertical profiles of groundwater fluxes from FO-DTS were found to correlate well with the relative magnitude of permeability of the hydrofacies identified with CPT profiles. FO-DTS could thus provide a qualitative or quantitative proxy for hydraulic conductivity and allow the recognition of hydrofacies at a fine scale. At the aquifer scale, the total flux measured by FO-DTS can also be compared to fluxes obtained from numerical models and thus provide a constraint to validate models. Overall, this study shows that not only does FO-DTS provide coherent results with other characterization methods, but it also adds the key measurement of groundwater flux that cannot be easily obtained by other means. FO-DTS thus has the potential to become a significant addition to existing characterization methods for granular aquifers.</div>

Download Full-text

Three-dimensional Bayesian geostatistical aquifer characterization at the Hanford 300 Area using tracer test data

Water Resources Research ◽

10.1029/2011wr010675 ◽

2012 ◽

Vol 48 (6) ◽

Cited By ~ 28

Author(s):

Xingyuan Chen ◽

Haruko Murakami ◽

Melanie S. Hahn ◽

Glenn E. Hammond ◽

Mark L. Rockhold ◽

...

Keyword(s):

Test Data ◽

Three Dimensional ◽

Tracer Test ◽

Aquifer Characterization

Download Full-text

Simulation Assessment of Direct Push Injection Logging for High‐Resolution Aquifer Characterization

Ground Water ◽

10.1111/gwat.12826 ◽

2018 ◽

Vol 57 (4) ◽

pp. 562-574 ◽

Cited By ~ 2

Author(s):

Gaisheng Liu ◽

Robert C. Borden ◽

James J. Butler

Keyword(s):

High Resolution ◽

Aquifer Characterization ◽

Direct Push

Download Full-text

Full waveform tomography for radially anisotropic structure: New insights into present and past states of the Australasian upper mantle

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2009.12.003 ◽

2010 ◽

Vol 290 (3-4) ◽

pp. 270-280 ◽

Cited By ~ 121

Author(s):

Andreas Fichtner ◽

Brian L.N. Kennett ◽

Heiner Igel ◽

Hans-Peter Bunge

Keyword(s):

Upper Mantle ◽

Anisotropic Structure ◽

Full Waveform ◽

Waveform Tomography

Download Full-text

Least‐squares inversion of in‐situ sonic Q measurements: Stability and resolution

Geophysics ◽

10.1190/1.1707056 ◽

2004 ◽

Vol 69 (2) ◽

pp. 378-385 ◽

Cited By ~ 9

Author(s):

Aristotelis Dasios ◽

Clive McCann ◽

Timothy Astin

Keyword(s):

High Resolution ◽

Least Squares ◽

Instantaneous Frequency ◽

Spectral Ratio ◽

Full Waveform ◽

Multiple Measurements ◽

Sandstone Reservoir ◽

Gas Bearing

We minimize the effect of noise and increase both the reliability and the resolution of attenuation estimates obtained from multireceiver full‐waveform sonics. Multiple measurements of effective attenuation were generated from full‐waveform sonic data recorded by an eight‐receiver sonic tool in a gas‐bearing sandstone reservoir using two independent techniques: the logarithmic spectral ratio (LSR) and the instantaneous frequency (IF) method. After rejecting unstable estimates [receiver separation <2 ft (0.61 m)], least‐squares inversion was used to combine the multiple estimates into high‐resolution attenuation logs. The procedure was applied to raw attenuation data obtained with both the LSR and IF methods, and the resulting logs showed that the attenuation estimates obtained for the maximum receiver separation of 3.5 ft (1.07 m) provide a smoothed approximation of the high‐resolution measurements. The approximation is better for the IF method, with the normalized crosscorrelation factor between the low‐ and high‐resolution logs being 0.90 for the IF method and 0.88 for the LSR method.

Download Full-text

Velocity model building by 3D frequency-domain, full-waveform inversion of wide-aperture seismic data

Geophysics ◽

10.1190/1.2957948 ◽

2008 ◽

Vol 73 (5) ◽

pp. VE101-VE117 ◽

Cited By ~ 93

Author(s):

Hafedh Ben-Hadj-Ali ◽

Stéphane Operto ◽

Jean Virieux

Keyword(s):

High Resolution ◽

Frequency Domain ◽

Distributed Memory ◽

Waveform Inversion ◽

Steepest Descent Method ◽

Frequency Domain Method ◽

Full Waveform Inversion ◽

Direct Solver ◽

Velocity Models ◽

Full Waveform

We assessed 3D frequency-domain (FD) acoustic full-waveform inversion (FWI) data as a tool to develop high-resolution velocity models from low-frequency global-offset data. The inverse problem was posed as a classic least-squares optimization problem solved with a steepest-descent method. Inversion was applied to a few discrete frequencies, allowing management of a limited subset of the 3D data volume. The forward problem was solved with a finite-difference frequency-domain method based on a massively parallel direct solver, allowing efficient multiple-shot simulations. The inversion code was fully parallelized for distributed-memory platforms, taking advantage of a domain decomposition of the modeled wavefields performed by the direct solver. After validation on simple synthetic tests, FWI was applied to two targets (channel and thrust system) of the 3D SEG/EAGE overthrust model, corresponding to 3D domains of [Formula: see text] and [Formula: see text], respectively. The maximum inverted frequencies are 15 and [Formula: see text] for the two applications. A maximum of 30 dual-core biprocessor nodes with [Formula: see text] of shared memory per node were used for the second target. The main structures were imaged successfully at a resolution scale consistent with the inverted frequencies. Our study confirms the feasibility of 3D frequency-domain FWI of global-offset data on large distributed-memory platforms to develop high-resolution velocity models. These high-velocity models may provide accurate macromodels for wave-equation prestack depth migration.

Download Full-text

Direct Push Technology and Application to Vertical Profiling of Hydraulic Conductivity in Unconsolidated Formations

9th ASME International Conference on Radioactive Waste Management and Environmental Remediation: Volumes 1, 2, and 3 ◽

10.1115/icem2003-4590 ◽

2003 ◽

Author(s):

Wesley McCall ◽

Thomas M. Christy ◽

James J. Butler

Keyword(s):

Hydraulic Conductivity ◽

Test Data ◽

Small Diameter ◽

Cost Effective ◽

Depth Interval ◽

Contaminant Migration ◽

Slug Tests ◽

Monitoring Wells ◽

Direct Push ◽

Vertical Profiling

Direct push (DP) methods provide a cost-effective alternative to conventional rotary drilling for investigations in unconsolidated formations. DP methods are commonly used for sampling soil gas, soil and groundwater; installing small-diameter monitoring wells; electrical logging; cone penetration testing; and standard penetration tests. Most recently, DP methods and equipment for vertical profiling of formation hydraulic conductivity (K) have been developed. Knowledge of the vertical and lateral variations in K is integral to understanding contaminant migration and, therefore, essential to designing an adequate and effective remediation system. DP-installed groundwater sampling tools may be used to access discrete intervals of the formation to conduct pneumatic slug tests. A small-diameter (38mm OD) single tube protected screen device allows the investigator to access one depth interval per advancement. Alternatively, a larger diameter (54mm OD) dual-tube groundwater profiling system may be used to access the formation at multiple depths during a single advancement. Once the appropriate tool is installed and developed, a pneumatic manifold is installed on the top of the DP rod string. The manifold includes the valving, regulator, and pressure gauge needed for pneumatic slug testing. A small-diameter pressure transducer is inserted via an airtight fitting in the pneumatic manifold, and a data-acquisition device connected to a laptop computer enables the slug test data to be acquired, displayed, and saved for analysis. Conventional data analysis methods can then be used to calculate the K value from the test data. A simple correction for tube diameter has been developed for slug tests in highly permeable aquifers. The pneumatic slug testing technique combined with DP-installed tools provides a cost-effective method for vertical profiling of K. Field comparison of this method to slug tests in conventional monitoring wells verified that this approach provides accurate K values. Use of this new approach can provide data on three-dimensional variations in hydraulic conductivity at a level of detail that has not previously been available. This will improve understanding of contaminant migration and the efficiency and quality of remedial system design, and ultimately, should lead to significant cost reductions.

Download Full-text