Detectability by Electromagnetic Depth Sounding - a data mining tool aiding interpretation of shallow sediments altered by oil and gas seeps

Shastri L Nimmagadda; Heinz Dreher; Kalyan Chakraborty

doi:10.1071/ASEG2007ab102

ISSN: 2202-0586
E-ISSN:

oa Detectability by Electromagnetic Depth Sounding - a data mining tool aiding interpretation of shallow sediments altered by oil and gas seeps
Authors Shastri L Nimmagadda^a, Heinz Dreher^b and Kalyan Chakraborty^c
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^a Wafra Joint Operations, KGOC, P O Box 9720, Al-Ahmadi, [email protected] ^b Curtin University of Technology, P O Box U1987, Perth, [email protected] ^c Kuwait Gulf Oil Company (KGOC), Al-Ahmadi, [email protected]
Publisher: Australian Society of Exploration Geophysicists
Source: ASEG Extended Abstracts, Volume 2007, Issue ASEG2007 - 19th Geophysical Conference, Dec 2007, p. 1 - 8
DOI: https://doi.org/10.1071/ASEG2007ab102
- Published online: 01 Dec 2007

Abstract

Summary

Electromagnetic depth sounding (EMDS) data are computed for simulated multi-layer earth models at different frequencies and geometries using digital linear filters. Detectability of sub-surface layers is computed as point-to-point difference of data instances between threelayer - homogeneous layer and two-layer - homogeneous layer media for similar range of frequencies. H and K-type earth models are also considered in the computations. Response curves, computed for two different layer earth media models are superimposed, thus, the separation between curves is the direct indication of the involved “detectability effect”. The degree of separation among response curves between two geometrically or parametrically changing data properties, called resolution, has direct impact on detectability effect.

Though detectability does not provide any qualitative or quantitative interpretation of data attributes, computed detectability effect significantly changes EMDS response resolution at varying layer-earth data attributes. Knowledge on strength of detectability and scalable properties among layer-earth media are interpreted based on resolution and coherency between two model response curves. Because of change in layered earth properties, varying horizontal and vertical resolution and coherency attributes between response curves provide considerable detectability effect. This process, termed as data-mining, facilitates extraction of knowledge of layer properties within multi-layer earth media. This detectability effect provides knowledge of n-layer-earth simulation, which can effectively respond to and aid the interpretation of actual geological models deduced from experimental data. These studies could prove to be useful for investigating shallow petroleum oil and gas seeps and their associated sediment alterations in the basin margin areas.

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References

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Article Type: Research Article

Keyword(s): Central Frequency Sounding (CFS); detectability; Multi-layer earth simulation; oil seepage

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