A Fast Inversion Method for Interpreting Single-Hole Electromagnetic Data

단일 시추공 전자탐사 자료 해석을 위한 빠른 역산법

  • Kim, Hee-Joon (Department of Environmental Exploration Engineering, Pukyong National University) ;
  • Lee, Jung-Mo (Department of Geology, Kyungpook National University)
  • Published : 2002.11.01

Abstract

A computationally efficient inversion scheme has been developed using the extended Born or localized nonlinear approximation to analyze electromagnetic fields obtained in a single-hole environment. The medium is assumed to be cylindrically symmetric about the borehole, and to maintain the symmetry vertical magnetic dipole source is used throughout. The efficiency and robustness of an inversion scheme is very much dependent on the proper use of Lagrange multiplier, which is often provided manually to achieve desired convergence. In this study, an automatic Lagrange multiplier selection scheme has been developed to enhance the utility of the inversion scheme in handling field data. The inversion scheme has been tested using synthetic data to show its stability and effectiveness.

단일 시추공 환경에서 얻어지는 전자기장을 해석하기 위해 확장 Born 혹은 국소비선형 근사를 이용한 계산시간이 짧고 효율적인 역산법을 만들었다. 매질은 시추공에 관해 축대칭이라 가정하였으며 그 대칭성을 유지하기 위해 수직 자기 쌍극자원을 사용하였다. 역산법의 효율성과 안정성은 적절한 라그랑지계수의 사용에 크게 의존하지만 이는 일반적으로 원하는 수렴성을 달성하기 위해 수작업으로 결정된다. 본 연구에서는 현장 자료를 다루는 역산법의 효율을 향상하기 위해 라그랑지계수의 자동결정법을 개발하였다. 그 역산법의 안정성과 효율성은 이론모델링 자료를 사용하여 검토되었다.

Keywords

References

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