Three-dimensional electromagnetic modeling and inversion on massively parallel computers
- Sandia National Labs., Albuquerque, NM (United States). Geophysics Dept.
This report has demonstrated techniques that can be used to construct solutions to the 3-D electromagnetic inverse problem using full wave equation modeling. To this point great progress has been made in developing an inverse solution using the method of conjugate gradients which employs a 3-D finite difference solver to construct model sensitivities and predicted data. The forward modeling code has been developed to incorporate absorbing boundary conditions for high frequency solutions (radar), as well as complex electrical properties, including electrical conductivity, dielectric permittivity and magnetic permeability. In addition both forward and inverse codes have been ported to a massively parallel computer architecture which allows for more realistic solutions that can be achieved with serial machines. While the inversion code has been demonstrated on field data collected at the Richmond field site, techniques for appraising the quality of the reconstructions still need to be developed. Here it is suggested that rather than employing direct matrix inversion to construct the model covariance matrix which would be impossible because of the size of the problem, one can linearize about the 3-D model achieved in the inverse and use Monte-Carlo simulations to construct it. Using these appraisal and construction tools, it is now necessary to demonstrate 3-D inversion for a variety of EM data sets that span the frequency range from induction sounding to radar: below 100 kHz to 100 MHz. Appraised 3-D images of the earth`s electrical properties can provide researchers opportunities to infer the flow paths, flow rates and perhaps the chemistry of fluids in geologic mediums. It also offers a means to study the frequency dependence behavior of the properties in situ. This is of significant relevance to the Department of Energy, paramount to characterizing and monitoring of environmental waste sites and oil and gas exploration.
- Research Organization:
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 212573
- Report Number(s):
- SAND-96-0582; ON: DE96008728; TRN: AHC29608%%118
- Resource Relation:
- Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
99 MATHEMATICS
COMPUTERS
INFORMATION SCIENCE
MANAGEMENT
LAW
MISCELLANEOUS
02 PETROLEUM
03 NATURAL GAS
54 ENVIRONMENTAL SCIENCES
ELECTROMAGNETIC SURVEYS
MATHEMATICAL MODELS
PETROLEUM DEPOSITS
NATURAL GAS DEPOSITS
SANITARY LANDFILLS
FINITE DIFFERENCE METHOD
COMPUTER ARCHITECTURE
PARALLEL PROCESSING
USES
MONITORING
SITE CHARACTERIZATION