지구물리와물리탐사 (Geophysics and Geophysical Exploration)

  • 제7권1호
  • /
  • Pages.51-55
  • /
  • 2004
  • /
  • 1229-1064(pISSN)
  • /
  • 2384-051X(eISSN)
한국지구물리·물리탐사학회 (Korean Society of Earth and Exploration Geophysicists)
권호 표지

Efficient crosswell EM Tomography using localized nonlinear approximation

  • Kim Hee Joon (Department of Environmental Exploration Engineering, Pukyong National University) ;
  • Song Yoonho (Korea Instituter of Geoscience & Mineral Resources) ;
  • Lee Ki Ha (Ernest Orlando Lawrence Berkeley National Laboratory) ;
  • Wilt Michael J. (ElectroMagnetic Instruments, Inc.)
  • 발행 : 2004.02.01
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초록

This paper presents a fast and stable imaging scheme using the localized nonlinear (LN) approximation of integral equation (IE) solutions for inverting electromagnetic data obtained in a crosswell survey. The medium is assumed to be cylindrically symmetric about a source borehole, and to maintain the symmetry a vertical magnetic dipole is used as a source. To find an optimum balance between data fitting and smoothness constraint, we introduce an automatic selection scheme for a Lagrange multiplier, which is sought at each iteration with a least misfit criterion. In this selection scheme, the IE algorithm is quite attractive for saving computing time because Green's functions, whose calculation is a most time-consuming part in IE methods, are repeatedly re-usable throughout the inversion process. The inversion scheme using the LN approximation has been tested to show its stability and efficiency, using both synthetic and field data. The inverted image derived from the field data, collected in a pilot experiment of water-flood monitoring in an oil field, is successfully compared with that derived by a 2.5-dimensional inversion scheme.

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참고문헌

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