Time-lapse Inversion of Small Loop EM Data

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2008 Vol.45, Issue 1 Preview Page Next Page

Time-lapse Inversion of Small Loop EM Data 소형루프 전자탐사 자료의 시간경과 역산: 김기주, 조인기, 송성호
Ki-Ju Kim, In-Ky Cho and Sung-Ho Song

29 February 2008. pp. 34-41

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Abstract

Small loop electromagnetic (EM) method has the ability to provide continuous conductivity distribution at shallow depth. Especially, this method is very suitable for monitoring conductivity variation in the subsurface because data acquisition is very rapid and non-destructive. In this study, we developed a time-lapse inversion algorithm to effectively interpret monitoring data. The developed inversion algorithm imposes a big penalty on model parameter with small change, while a minimal penalty on model parameter with large change compared with a reference model. Consequently, inversion result shows a focused image where model parameters changed greatly. Applying the method on the inversion of synthetic 2.5D small loop EM monitoring data, we can ensure that it is effective in the detection of areas which show great change between a reference and time-lapse model.

Keywords

Small loop EM

Time-lapse inversion

Monitoring

소형루프 전자탐사법은 지하 천부의 전기전도도 분포에 관한 연속적인 영상을 제공해 준다. 특히 이 방법은 자료획득이 신속하고 비파괴 방법이므로 모니터링에 효과적인 물리탐사법 중 하나이다. 이 연구에서는 모니터링 자료의 해석을 위하여 시간경과 역산법을 개발하였다. 개발된 역산법은 기준모델에 비하여 변화가 큰 모델변수에는 약한 제한을, 변화가 미미한 모델변수에는 강한 제한을 가하여, 결과적으로 역산 결과는 변화가 큰 영역을 뚜렷하게 영상화하게 된다. 이 시간경과 역산법을 소형루프 전자탐사 자료의 역산에 적용한 결과 기준모델에 비하여 변화가 큰 영역을 효과적으로 탐지할 수 있었다.

키워드

소형루프 전자탐사

시간경과 역산법

모니터링

References

조인기, 강미경, 김기주, 2006, “주 대상체 강조법에 의한 소형루프 전자탐사 자료의 역산”, 물리탐사, Vol. 9, pp. 299-303.
조인기, 서정희, 1998, “확장된 Born 근사에 의한 시추공간 전자탐사 2.5차원 모델링”, 물리탐사, Vol. 1, pp. 127-135.
조인기, 송성호, 서정희, 2007, “확장 Born 근사에 의한 소형루프 전자탐사법의 신속한 2.5차원 모델링”, 물리탐사, Vol. 10, pp. 308-313.
조인기, 심현미, 1998, “확장된 Born 근사에 의한 EM 토모 그래피”, 물리탐사, Vol. 1, pp. 155-160.
Constable, S. C., Parker, R. L., and Constable, C. G., 1987, “Occam’s inversion: a practical algorithm for generating smooth models from EM sounding data,” Geophysics, Vol. 52, pp. 289-300.
Day-Lewis, F. D., Harris, J. M., and Gorelick, S. M., 2002, “Time-lapse inversion of crosswell radar data,” Geophysics, Vol. 66, pp. 1740-1752.
Habashy, T. M., Groom, R. W. and Spies, B. R., 1993, “Beyond the Born and Rytov approximations,” Journal of Geophysical Research, Vol. 98, pp. 1759-1775.
Kim, J. H., 2006, “Least-squares inversion of DC resistivity data acquired over dynamically changing earth model,” Proceedings of Near Surface 2006, the 12’th European meeting of Environmental and Engineering Geophysics, European Association of Geoscientists and Engineers, 4-6 Sep., Helsinki, Finland, B030.
LaBrecque, D. J., and Yang, X., 2001, “Difference inversion of ERT data, A fast inversion method for 3-D in-situ monitoring,” Journal of Environmental and Engineering Geophysics, Vol. 6, pp. 83-89.
Loke, M. H., 1999, “Time-lapse resistivity imaging inversions,” Environmental and Engineering Geophysical Society European Section, Meeting, Proceedings, Em1. Oldenborger, G. A., Knoll, M. D., Routh, P. S., and
LaBrecque, D. J., 2007, “Time-lapse ERT monitoring of an injection/withdrawal experiment in a shallow unconfined aquifer,” Geophysics, Vol. 72, pp. F177-F188. Portniaguine, O., and Zhdanov, M. S., 1999, “Focusing geophysical inversion images,” Geophysics, Vol. 64, pp. 874-887.
Torres-Verdin, C. and Habashy, T. M., 1995, “Rapid 2.5 dimensional forward modeling and inversion via a new nonlinear scattering approximation,” Radio Science, Vol. 29, pp. 1051-1079.
Yi, M. J., Kim, J. H., and Chung, S. H., 2003, “Enhancing the resolving power of least-squares inversion with active constraint balancing,” Geophysics, Vol. 68, pp. 931-941.

Information

Publisher :The Korean Society of Mineral and Energy Resources Engineers
Publisher(Ko) :한국자원공학회
Journal Title :Journal of the Korean Society for Geosystem Engineering
Journal Title(Ko) :한국지구시스템공학회지
Volume : 45
No :1
Pages :34-41

[1] 조인기, 강미경, 김기주, 2006, “주 대상체 강조법에 의한 소형루프 전자탐사 자료의 역산”, 물리탐사, Vol. 9, pp. 299-303.

[2] 조인기, 서정희, 1998, “확장된 Born 근사에 의한 시추공간 전자탐사 2.5차원 모델링”, 물리탐사, Vol. 1, pp. 127-135.

[3] 조인기, 송성호, 서정희, 2007, “확장 Born 근사에 의한 소형루프 전자탐사법의 신속한 2.5차원 모델링”, 물리탐사, Vol. 10, pp. 308-313.

[4] 조인기, 심현미, 1998, “확장된 Born 근사에 의한 EM 토모 그래피”, 물리탐사, Vol. 1, pp. 155-160.

[5] Constable, S. C., Parker, R. L., and Constable, C. G., 1987, “Occam’s inversion: a practical algorithm for generating smooth models from EM sounding data,” Geophysics, Vol. 52, pp. 289-300.

[6] Day-Lewis, F. D., Harris, J. M., and Gorelick, S. M., 2002, “Time-lapse inversion of crosswell radar data,” Geophysics, Vol. 66, pp. 1740-1752.

[7] Habashy, T. M., Groom, R. W. and Spies, B. R., 1993, “Beyond the Born and Rytov approximations,” Journal of Geophysical Research, Vol. 98, pp. 1759-1775.

[8] Kim, J. H., 2006, “Least-squares inversion of DC resistivity data acquired over dynamically changing earth model,” Proceedings of Near Surface 2006, the 12’th European meeting of Environmental and Engineering Geophysics, European Association of Geoscientists and Engineers, 4-6 Sep., Helsinki, Finland, B030.

[9] LaBrecque, D. J., and Yang, X., 2001, “Difference inversion of ERT data, A fast inversion method for 3-D in-situ monitoring,” Journal of Environmental and Engineering Geophysics, Vol. 6, pp. 83-89.

[10] Loke, M. H., 1999, “Time-lapse resistivity imaging inversions,” Environmental and Engineering Geophysical Society European Section, Meeting, Proceedings, Em1. Oldenborger, G. A., Knoll, M. D., Routh, P. S., and

[11] LaBrecque, D. J., 2007, “Time-lapse ERT monitoring of an injection/withdrawal experiment in a shallow unconfined aquifer,” Geophysics, Vol. 72, pp. F177-F188. Portniaguine, O., and Zhdanov, M. S., 1999, “Focusing geophysical inversion images,” Geophysics, Vol. 64, pp. 874-887.

[12] Torres-Verdin, C. and Habashy, T. M., 1995, “Rapid 2.5 dimensional forward modeling and inversion via a new nonlinear scattering approximation,” Radio Science, Vol. 29, pp. 1051-1079.

[13] Yi, M. J., Kim, J. H., and Chung, S. H., 2003, “Enhancing the resolving power of least-squares inversion with active constraint balancing,” Geophysics, Vol. 68, pp. 931-941.

Journal of the Korean Society of Mineral and Energy Resources Engineers ISSN:2288-0291(Print) 2288-2790(Online) 한국자원공학회지

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