Surface and borehole electromagnetic imaging of conducting contaminant plumes. 1997 annual progress report
'Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The EM source field is produced by induction coil (magnetic dipole) transmitters deployed at the surface or in boreholes. Vertical and horizontal component magnetic field detectors are deployed in other boreholes or on the surface. Sources and receivers are typically deployed in a configuration surrounding the region of interest. The goal of this procedure is to image electrical conductivity variations in the earth, much as x-ray tomography is used to image density variations through cross-sections of the body. Although such EM field techniques have been developed and applied, the algorithms for inverting the magnetic data to produce the desired images of electrical conductivity have not kept pace. One of the main reasons for the lag in the algorithm development has been the fact that the magnetic induction problem is inherently three dimensional: other imaging methods such as x-ray and seismic can make use of two-dimensional approximations that are not too far from reality, but the author does not have this luxury in EM induction tomography. In addition, previous field experiments were conducted at controlled test sites that typically do not have much external noise or extensive surface clutter problems often associated with environmental sites. To use the same field techniques in environments more typical of cleanup sites requires a new set of data processing tools to remove the effects of both noise and clutter. The goal of this project is to join theory and experiment to produce enhanced images of electrically conducting fluids underground, allowing better localization of contaminants and improved planning strategies for the subsequent remediation efforts. After explaining the physical context in more detail, this report will summarize the progress made in the first year of this project: (1) on code development and (2) on field tests of these methods. The author concludes with a brief statement of the research directions for the second year of the project.'
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE Office of Environmental Management (EM), Office of Science and Risk Policy
- OSTI ID:
- 13558
- Report Number(s):
- EMSP-55011-97; ON: DE00013558
- Country of Publication:
- United States
- Language:
- English
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Surface and Borehole Electromagnetic Imaging of Conducting Contaminant Plumes
Surface and borehole electromagnetic imaging of conducting contaminant plumes. 1998 annual progress report