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The effect of intra-trappean heterogeneities on seismic data: A case study from the Deccan Traps

The effect of intra-trappean heterogeneities on seismic data: A case study from the Deccan Traps
The effect of intra-trappean heterogeneities on seismic data: A case study from the Deccan Traps
Hydrocarbon exploration interests have renewed the need for developing new sub basalt imaging techniques. One of the most important problems encountered today is seismic imaging below basalt. In recent years, this problem appears to have been overcome partly by using long offset seismic data. However near offset data are yet to be fully utilised due to the complex waveform caused by the surface as well as internal heterogeneity of the basalts. The near normal incidence data, which influence the sub-basalt imaging, are highly useful to understand the internal structure within a basalt layer. The use of converted waves for such targets has been proposed as an alternative in a rather homogeneous basalt layer. With a few synthetic modelling exercises here we highlight the practical difficulties in dealing with more realistic and heterogeneous basalt flow. Full waveform seismograms are computed to understand the effects of intra-trappean sediments on the seismic data. A case study from the Deccan Traps of India is presented in this paper. First, we discuss the effects of intercalated sediments on the overall seismic image. Later, the sonic log data from the field are used to compute the full wave-field response using the reflectivity method and compared with the field data. The feasibility of using mode converted waves (P to S and vice-versa at the top and bottom basalt interfaces) for sub-basalt imaging in Kutch region is discussed through a series of velocity-depth profiles. By comparing with the field data we demonstrate that the effects of multiple thin layering within the basalt can strongly deteriorate the image we seek to interpret and exploit.
Sub-basalt imaging, Kutch, Deccan Traps, Reflectivity, Full-waveform modelling
1672-7975
183-193
Pandey, D K
914982ed-83b0-4013-8b3d-3005104a6d16
Singh, S C
48a6a41f-2be1-42e6-bd88-a94b427fb449
Sinha, M C
794c3012-d0e8-4d2f-b328-c8cfd56c5976
MacGregor, L M
c69dab2d-2dd5-4d2d-99aa-bb3bebdb7564
Pandey, D K
914982ed-83b0-4013-8b3d-3005104a6d16
Singh, S C
48a6a41f-2be1-42e6-bd88-a94b427fb449
Sinha, M C
794c3012-d0e8-4d2f-b328-c8cfd56c5976
MacGregor, L M
c69dab2d-2dd5-4d2d-99aa-bb3bebdb7564

Pandey, D K, Singh, S C, Sinha, M C and MacGregor, L M (2007) The effect of intra-trappean heterogeneities on seismic data: A case study from the Deccan Traps. Applied Geophysics, 4 (3), 183-193. (doi:10.1007/s11770-007-0033-8).

Record type: Article

Abstract

Hydrocarbon exploration interests have renewed the need for developing new sub basalt imaging techniques. One of the most important problems encountered today is seismic imaging below basalt. In recent years, this problem appears to have been overcome partly by using long offset seismic data. However near offset data are yet to be fully utilised due to the complex waveform caused by the surface as well as internal heterogeneity of the basalts. The near normal incidence data, which influence the sub-basalt imaging, are highly useful to understand the internal structure within a basalt layer. The use of converted waves for such targets has been proposed as an alternative in a rather homogeneous basalt layer. With a few synthetic modelling exercises here we highlight the practical difficulties in dealing with more realistic and heterogeneous basalt flow. Full waveform seismograms are computed to understand the effects of intra-trappean sediments on the seismic data. A case study from the Deccan Traps of India is presented in this paper. First, we discuss the effects of intercalated sediments on the overall seismic image. Later, the sonic log data from the field are used to compute the full wave-field response using the reflectivity method and compared with the field data. The feasibility of using mode converted waves (P to S and vice-versa at the top and bottom basalt interfaces) for sub-basalt imaging in Kutch region is discussed through a series of velocity-depth profiles. By comparing with the field data we demonstrate that the effects of multiple thin layering within the basalt can strongly deteriorate the image we seek to interpret and exploit.

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More information

Published date: September 2007
Keywords: Sub-basalt imaging, Kutch, Deccan Traps, Reflectivity, Full-waveform modelling

Identifiers

Local EPrints ID: 49315
URI: http://eprints.soton.ac.uk/id/eprint/49315
ISSN: 1672-7975
PURE UUID: 3f0a9527-7c79-4516-a3e6-28c089f25ff6

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Date deposited: 30 Oct 2007
Last modified: 15 Mar 2024 09:54

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Contributors

Author: D K Pandey
Author: S C Singh
Author: M C Sinha
Author: L M MacGregor

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