Pennsylvania Water Science Center




Field Demonstration:
Techniques for Characterizing Ground-Water Flow and Contaminant Transport in Fractured Rock


Hydrogeologic Reconaissance

D. Borehole Logging: Caliper, gamma, electromagnetic, electric, and fluid logging. Borehole geophysical logging provides a first look at information in boreholes, not only information on rock properties and fractures, but also water quality. When used in conjuction with other borehole information and hydraulic and tracer testing, provides a basis for developing a conceptual model of fractures, fluid movement and chemical migration. (John Williams and Pierre Lacombe)

Borehole Logging Presentation with Tools
Acoustic Televiewer Presentation

E. Digital Acoustic Televiewer: Borehole imaging techniques provide information on fracture location, orientation, and other properties needed to develop conceptual model of flow and transport in fractures in the subsurface. The tool and data visualization will be demonstrated and examples of use of this information in contaminated site assessment will be presented. (Roger Morin and Phil Bird)

F. Surface Geophysics: Standard and azimuthal resistivity, seismic, and electro-magnetic surveys. Surface geophysics encompasses a variety of techniques for recon that identify location of major fracture zones and/or orientation of pervasive sets of fractures. (Pete Haeni)

Presentation of Surface Geophysics Equipment
Presentation of Borehole Radar Equipment

G. Borehole Radar: Single- and cross-hole methods for imaging fracture zones beyond and between boreholes. USGS is actively involved in developing tools and analysis methods in this rapidly evolving field. Radar can be used to obtain three-dimensional information about the formation using single-hole directional tools or cross-hole tools and tomography. (John Lane)

H. Digital Borehole TV Camera: Downhole television augments other logging tools by providing high-resolution lithology and visual confirmation of fracture identification. It also provides visual inspection of borehole, potential for identifying in situ contamination (e.g., free product--LNAPL or DNAPL--at contaminated sites), fracture mineralization and biological coatings that may be critical to contaminant fate. (Carole Johnson)

Well with Digital Camera Logging
Flowmeter Equipment

I. Borehole Flowmeter: Heat-pulse and electro-magnetic methods to determine borehole flow and identify transmissive fractures. A rapid method pioneered by USGS for identifying vertical pressure gradients between water producing zones. In conjunction with hydraulic testing, can quickly identify major producing zones and complex plumbing in open-borehole settings. (Fred Paillet and Randy Conger)

Single-Well Testing

A. Air-Pressurized Slug Test: A single-hole hydraulic test to quantify hydraulic properties of formation. Pioneered by USGS, this method allows small-scale testing of subsurface hydraulic properties with minimal contamination of equipment (only a pressure transducer enters the water column in the borehole). Rapid interpretation is facilitated by USGS analytical solutions and graphical PC programs. (Earl Greene)

Wellhead with Air Slug Equipment
Ultra-Clean Sampling Procedures

B. Collection of Geochemical Data: Collection of water samples in fractured rock and the need to understand hydraulic properties of fractures. Problems with open hole sample collection. Sampling using packers. Analyses conducted (basic geochemistry --cations and anions, isotopes, dissolved gases, age-dating tracers). Application to contaminated sites and understanding fractured rock. USGS ultra-clean NAWQA (National Water Quality Assessment) sampling protocols. (Allen Shapiro and Zoltan Szabo)

J. Single-Hole Fluid Injection Test: Single-hole hydraulic test using packers to quantify hydraulic properties of individual sections of the formation over the length of the borehole. Especially useful for measuring properties of less-productive portions of formation that may control contaminant transport and retention. Demonstrated in see-thru casing at surface with examples of its use to quantify spatial variability of hydraulic conductivity. (Claire Tiedeman)

Transparent Casing with Packers

Multi-Well Testing

Constant-Rate Pumping: (At Station C) The extended-duration pumping test with multiple observation wells and multiple packer-isolated intervals remains a cost-effective tool for assessing field-scale hydraulic propeties. However, interpretation of test results in fractured rock is difficult and often cannot be done with standard methods. A live test will be conducted throughout the day and examples presented of standard and non-standard analysis methods at this and other USGS sites.

Presentation on Aquifer Testing
Tracer Testing with Packer

C. Tracer Testing: In situ tracer tests are the only means of identifying crucial parameters needed for understanding chemical migration in fractured rock (porosity, matrix diffusion). There are many types of tracer tests using various tracers. Tests must be conducted rigorously to quantify transport properties (one must know what is injected)--USGS has developed equipment to conduct rigorous tracer tests. A live tracer test will be conducted throughout the day with realtime data analysis. (Glen Carleton and Dan Goode)


K. Quantitative Analysis of Fluid and Chemical Migration: Collection and analysis of geophysical, geochemical and hydraulic information to identify complex hydraulic terranes. Modeling for testing scenarios of heterogeneity. Modeling/synthesis of data for parameter identification and parameter distribution. Ground-water flow modeling in a heterogeneous formations will be demonstrated with USGS models and visualization tools. (Paul Hsieh)

Computer Simulation

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