Geophysics and Geophysical Exploration (지구물리와물리탐사)

Korean Society of Earth and Exploration Geophysicists (한국지구물리·물리탐사학회)
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.)
  • Published : 2004.02.01
Download PDF
⟨ Previous Next ⟩

Abstract

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.

Keywords

References

  1. Alumbaugh, D.L. and Morrison, H.F., 1995, Theoretical and practical considerations for crosswell electromagnetic tomography assuming a cylindrical geometry: Geophysics, 60, 846-870
  2. Alumbaugh, D.L., and Newman, G.A., 1997, Three-dimensional massively parallel electromagnetic inversion -II. Analysis of crosswell electromagnetic experiment: Geophys. J. Int., 128, 355-363
  3. Constable, S.C., Parker, R.L., and Constable, C.G., 1987, A practical algorithm for generating smooth models from electromagnetic sounding data: Geophysics, 52, 289-300
  4. Constable, S.C., Parker, R.L., and Constable, C.G., 1987, A practical algorithm for generating smooth models from electromagnetic sounding data: Geophysics, 52, 289-300
  5. Habashy, T.M., Groom, R.M., and Spies, B.R., 1993, Beyond the Bom and Rytov approximations: a nonlinear approach to electromagnetic scattering: J. Geophys. Res., 98, 1795-1775
  6. Hohmann, G.W., 1975, Three-dimensional induced polarization and EM modeling: Geophysics, 40, 309-324
  7. Hohmann, G.W., 1988, Numehcal modeling for etectromagnetic methods of geophysics, in Nabighian, M.N., (ed.), Electromagnetic Methods in Applied Geophysics, Vol. 1: Soc. Expl. Geophys., 313-363
  8. Lee, K.H., Kim, H.J., and Uchida, T., 2004, Electromagnetic fields in steel-cased borehole: Geophys. Prosp., 52, (in press)
  9. Lee, K.H., Kim, H.J., and Wilt, M., 2002, Efficient imaging of single-holeelectromagnetic data: GRC Transactions, 26, 399-404
  10. Newman, G.A., 1995, Crosswell electromagnetic inversion using integral and differential equations: Geophysics, 60, 899-911
  11. Parker, R.L., 1994, Geophysical Inverse Theory: Phnceton University Press
  12. Raiche, A.P., 1974, An integral equation approach to 3D modeling: Geophys. J. Roy. astr. Soc., 36, 363-376
  13. Song, Y., Kim, J.-H., and Chung, S.-H., 2001, An effcient 2.5-D inversion of loop-loop EM data, Proc. 5th SEGJ Int. Symp., 153-160
  14. Tikhonov, A.N., and Arsenin, V.Y., 1977, Solutions to Ill-Posed Probtems'. John Wiley and Sons, Inc
  15. Ward, S.H., and Hohmann, G.W., 1988, Electromagnetic theory for geophysical applications, in Nabighian, M.N., (ed.), Electromagnetic Methods in Applied Geophysics, Vol. 7: Soc. Expl. Geophys., 131-311
  16. Wilt, M.J., Alumbaugh, D.L., Morrison, H.F., Becker, A., Lee, K.H., and Deszcz-Pan, M., 1995, Crosshole electromagnetic tomography: System design considerations and field results: Geophysics, 60, 871-885
  17. Wilt, M.J., Zhang, R, Osato, K., and Tsuneyama, F., 2001, Crosswell EM studies at the Ellis Lease, Lost Hills Califomia: Proc. 5th SEGJ Int. Symp., 243-250
  18. Zhdanov, M.S., and Fang, S., 1996, Quasi-Iinear approxiniation m 3-D EM modeling: Geophysics, 61, 646-665
  19. Zhou, Q., Becker, A., and Monison, H.F., 1993, Audio-frequency electromagnetic tomography in 2-D: Geophysics, 58, 482-495