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Journal of Applied Geophysics 43 2000 215–226 www.elsevier.nlrlocaterjappgeo
Use of four-dimensional ground penetrating radar and advanced visualization methods to determine subsurface fluid migration
Ralf Birken , Roelof Versteeg
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Lamont-Doherty Earth ObserÕatory of Columbia UniÕersity, 61 Route 9W, Palisades, NY 10964-8000, USA Received 13 October 1998; received in revised form 26 February 1999; accepted 15 March 1999
Abstract
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Four-dimensional 4D or time-lapse three-dimensional 3D ground penetrating radar surveys can be used to monitor and image subsurface fluid flow. This information can be used to create a model of hydrogeological properties. The massive
amount of data, which is present in and can possibly be generated from 4D GPR data sets, precludes a manual interpretation. Consequently, 4D data sets have to be processed and visualized in a way that extracts models and allows for data
visualization in a semi-automatic way. The principles behind such an approach are applied to the Borden data set, which is used to demonstrate how advanced visualization can assist in the interpretation of raw and processed data. In the Borden data
set, changes in reflectivity between different time-steps unveil areas of fluid migration in three dimensions. The combination
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of these reflectivity changes between different combinations of the 3D subsets of the 4D data set is used to create a model of hydrogeological properties. While this model does not yield a quantitative description of porosity, permeability or
hydraulic conductivity, it is a qualitative proxy for a combination of these properties. q 2000 Elsevier Science B.V. All rights reserved.
Keywords: GPR; Modeling; Visualization; Hydrogeology; Monitoring; DNAPLS
1. Introduction
One of the most complex problems in earth sciences is that of the determination of fluid
flow behavior such as flow pathways, flow ve- locity andror hydraulic conductivity in a het-
erogeneous subsurface. Information on fluid
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flow behavior both present and predicted is
Corresponding author. Tel.: q1-914-365-8327; fax: q1-914-365-8150; e-mail: birkenldeo.columbia.edu
1
E-mail: versteegldeo.columbia.edu.
needed for the determination of the size and shape of groundwater recharge areas, the assess-
ment of contamination impact of spills and plumes, and the planning and assessment of
remediation efforts. For all these problems, it is recognized that a good knowledge of the three-
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dimensional 3D values of hydraulic conductiv- ity is essential, yet most often, the only knowl-
edge available on the hydraulic conductivity is that deduced from a number of sampling wells
and pumping test experiments. These experi-
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ments only give a poor bulk approximation of the hydraulic conductivity, and consequently,
0926-9851r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
. PII: S 0 9 2 6 - 9 8 5 1 9 9 0 0 0 6 0 - 9
the predictions of fluid flow behavior based on these approximations are more often than not
unsuccessful. There is thus a strong need for a method,
which can generate a reliable subsurface model of hydraulic conductivity. Recent Ground Pene-
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trating Radar GPR work has demonstrated the feasibility of surface and borehole radar to de-
Ž tect fluid movement Brewster and Annan, 1994;
. Lane et al., 1996 . Research conducted in time-
dependent monitoring of oil and gas reservoirs, using multiple instances of 3D seismic data sets,
has demonstrated the feasibility of extracting a time- and space-dependent model of subsurface
fluid flow. From this a model of subsurface, hydrogeological
properties can
be derived
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Anderson et al., 1991, 1994 . Thus, four-di- Ž
. mensional 4D or time-lapse 3D GPR could be
the method to provide models of hydrogeologi- cal properties. The extraction of these models
from the 4D data and the visualization of 4D radar data are the topic of this paper.
2. 4D-seismic and 4D-GPR
