FY2003 Advanced Geophysical Methods Development: Processing Cross-Hole Borehole-Radar Tomography Data

As part of the USGS Office of Ground Water, Branch of Geophysics (OGW BG) applied geophysical research through the USGS Toxic Substances Hydrology Program, advanced methods for processing borehole-radar tomography data are being developed. The goal of this work is to improve the tools available to the USGS for cross-hole borehole-radar data processing and analysis.

During FY2003, work included dynamic imaging of saline tracer transport in fractured rock using difference-attenuation radar tomography. The method was applied to data collected several years ago at the USGS Toxic Substances Hydrology Program Mirror Lake research site, New Hampshire.

Work also included development of an object-based method for inversion of cross-hole borehole-radar data in order to better estimate the area affected by vegetable oil tracers being injected into the ground. This inversion method was applied to radar tomography data collected during the injection of a vegetable-oil emulsion used for biostimulation in a U.S. Navy remediation pilot project in Fridley, Minnesota. Rather than estimating grid-cell values of radar velocity, this new inversion method identifies the boundaries of, and radar velocity within, the vegetable-oil plume being monitored. In tests using both field data and synthetic data examples, this new method was shown to provide a better characterization of the distribution and saturation of the vegetable oil when compared with the results of traditional inversion approaches.

FY2003 OGW BG work has also investigated the limitations and pitfalls of different approaches to determining relationships between hydrologic and geophysical measurements and the usefulness of geophysical tomograms for input to geostatistical simulation of hydrologic properties. Tomograms of cross-hole radar velocity can be used to develop estimates of permeability and other hydrologic properties of the subsurface region between wells. However, the resolution of the tomogram varies spatially between wells, requiring extra caution when interpreting and using cross sections of permeability that are calculated from geophysical data. A modeling approach was developed to facilitate the design of tomographic surveys and to examine how the resolution varies with survey design. As part of this work, OGW BG has started to develop tomographic forward modeling and inversion software.

This research was funded by the USGS Toxic Substances Hydrology Program.

This research was conducted by Fred Day-Lewis (USGS OGW BG) and John W. Lane, Jr. (USGS OGW BG) with assistance from OGW BG staff.

Recent publications:

Day-Lewis, F.D., and Lane, J.W., Jr., 2004, Assessing the resolution-dependent utility of tomograms for geostatistics: Geophysical Research Letters, Vol. 31, L07503, doi:10.1029/2004GL019617, 4p.

Day-Lewis, F.D. and Lane, J.W., Jr, 2003, Use of crosshole radar tomograms for geostatistical estimation and simulation of interwell permeability: Limitations due to tomographic resolution [abs.]: Eos Transactions, American Geophysical Union, v. 84, no. 46, Fall Meeting Suppl., Abstract H21F-02.

Day-Lewis, F.D., Singha, Kamini, and Binley, A.M., 2004, On the pitfalls and limitations of applying petrophysical models to tomograms - examples in cross-borehole radar and electrical resistivity tomography: EOS Trans., AGU, v. 85, no. 17, Jt. Assem. Suppl., Abstract NS13A-03.

Day-Lewis, F. D., Lane, J.W., Jr., Harris, J.M., and Gorelick, S.M., 2003, Time-lapse imaging of saline tracer tests using cross-borehole radar tomography: Water Resources Research, Vol. 39, no. 10, 14 p.,1290, doi:10.1029/2002WR001722.

Lane, J.W., Jr, 2003, Time-lapse geophysics for aquifer characterization and remediation monitoring [abs.]: Eos Transactions, American Geophysical Union, v. 84, no. 46, Fall Meeting Suppl., Abstract H21F-01.

Lane, J.W., Jr., Casey, C.C., Day-Lewis, F.D., Witten, A., and Versteeg, R.J., 2004, Use of borehole radar methods and borehole geophysical logs to monitor a field-scale vegetable oil biostimulation pilot project at Fridley, Minnesota, in Proceedings of the Fourth International Conference on Remediation of Chlorinated and Recalcitrant Compounds, May 24-27, 2004, Monterrey California. Proceedings: Battelle Memorial Institute, CD-ROM, 9 pages.

Lane, J.W., Jr., Day-Lewis, F.D., Versteeg, R.J., and Casey, C.C., 2004, Object-based inversion of crosswell radar tomography data to monitor vegetable oil injection experiments: Journal of Environmental & Engineering Geophysics, vol.9, issue 2, p. 63-77.

Lane, J.W., Jr., Day-Lewis, F.D., Versteeg, R.J., Casey, C.C., and Joesten, P.K., 2004, Application of cross-borehole radar to monitor field-scale vegetable oil injection experiments for biostimulation, in Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), 22 to 26 February, 2004, Colorado Springs, Proceedings: Denver, Colorado, Environmental and Engineering Geophysical Society, CD-ROM, 20 p.

Lane, J.W., Jr., Day-Lewis, FD, Versteeg, R.J., And Casey, C.C., 2003, Object-based inversion of crosswell radar tomography data to monitor vegetable-oil injection experiment, in Symposium on the Application of Geophysics to Engineering and Environmental Problems (SAGEEP), April 6-10, 2003, San Antonio, Texas, Proceedings: Denver, Colorado, Environmental and Engineering Geophysics Society, CD-ROM, 27 p.

Day-Lewis, F.D., Harris, J.M., and Gorelick, S.M., 2002, Time-lapse inversion of crosswell radar data: Geophysics, v. 67 , no. 6, p. 1740-1752.