Universität zu Köln

Liu, Yajun, Yogeshwar, Pritam, Hu, Xiangyun, Peng, Ronghua, Tezkan, Buelent, Moerbe, Wiebke and Li, Jianhui (2020). Effects of electrical anisotropy on long-offset transient electromagnetic data. Geophys. J. Int., 222 (2). S. 1074 - 1090. OXFORD: OXFORD UNIV PRESS. ISSN 1365-246X

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Abstract

Electrical anisotropy of formations has been long recognized by field and laboratory evidence. However, most interpretations of long-offset transient electromagnetic (LOTEM) data arc based on the assumption of an electrical isotropic earth. Neglecting electrical anisotropy of formations may cause severe misleading interpretations in regions with strong electrical anisotropy. During a large scale LOTEM survey in a former mining area in Eastern Germany, data was acquired over black shale formations. These black shales are expected to produce a pronounced bulk anisotropy. Here, we investigate the effects of electrical anisotropy on LOTEM responses through numerical simulation using a finite-volume time-domain (FVTD) algorithm. On the basis of isotropic models obtained from LOTEM field data, various anisotropic models are developed and analysed. Numerical results demonstrate that the presence of electrical anisotropy has a significant influence on LOTEM responses. Based on the numerical modelling results, an isolated deep conductive anomaly presented in the 2-D isotropic LOTEM electric field data inversion result is identified as a possible artifact introduced by using an isotropic inversion scheme. Trial-and-error forward modelling of the LOTEM electric field data using an anisotropic conductivity model can explain the data and results in a reasonable quantitative data fit. The derived anisotropic 2-D model is consistent with the prior geological information.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Liu, Yajun UNSPECIFIED UNSPECIFIED UNSPECIFIED Yogeshwar, Pritam UNSPECIFIED UNSPECIFIED UNSPECIFIED Hu, Xiangyun UNSPECIFIED UNSPECIFIED UNSPECIFIED Peng, Ronghua UNSPECIFIED UNSPECIFIED UNSPECIFIED Tezkan, Buelent UNSPECIFIED UNSPECIFIED UNSPECIFIED Moerbe, Wiebke UNSPECIFIED UNSPECIFIED UNSPECIFIED Li, Jianhui UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-324498
DOI:	10.1093/gji/ggaa213
Journal or Publication Title:	Geophys. J. Int.
Volume:	222
Number:	2
Page Range:	S. 1074 - 1090
Date:	2020
Publisher:	OXFORD UNIV PRESS
Place of Publication:	OXFORD
ISSN:	1365-246X
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language INVERSION; 3D; CONDUCTIVITY; SOUNDINGS; RESPONSES Multiple languages Geochemistry & Geophysics Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/32449