Low velocity layer characterization in the Niger Delta: Implications for seismic reflection data quality

The problems of poor data quality and statics in seismic surveys have been attributed to lack of proper understanding of the low velocity layer characteristics of the area from which such data was acquired. Downhole seismic refraction survey was therefore conducted at twenty (20) borehole locations...

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Bibliographic Details
Published in:Journal of the Geological Society of India 2017-08, Vol.90 (2), p.187-195
Main Authors: Opara, A. I., Agoha, C. C., Okereke, C. N., Adiela, U. P., Onwubuariri, C. N., Okpono, J. O., Nosiri, O. P.
Format: Article
Language:English
Subjects:
Area
Boreholes
Computer programs
Consolidation
Corrections
Data acquisition
Earth and Environmental Science
Earth Sciences
Geology
Hydrogeology
Reflection
Seismic data
Seismic refraction
Seismic surveys
Software
Spatial discrimination
Surveying
Surveys
Velocity
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Summary:The problems of poor data quality and statics in seismic surveys have been attributed to lack of proper understanding of the low velocity layer characteristics of the area from which such data was acquired. Downhole seismic refraction survey was therefore conducted at twenty (20) borehole locations within parts of Niger Delta, Nigeria to determine the low velocity layer characteristics of the area using the Geometrics Stratavisor NZ11 instrument. The data was processed using Udysys software with spatial representation of the results presented. Static corrections were carried out on reflection seismic data acquired from the study area using Geoscribe II software to determine the effects of the low velocity layer on reflection seismic data in the area. Results of the study revealed that the velocity of the low velocity layer ranged between 144 and 996m/s with a regional average of 407m/s. The thickness of the low velocity layer varied between 3.0 and 9.6m with a mean value of 5.0m. Similarly, the velocity of the consolidated layer ranged between 1449 and 1812m/s with a mean value of 1738m/s. Results of the static correction carried out on the seismic reflection data revealed a substantial improvement in the resolution of the data after static correction. Based on these findings, it is therefore, recommended that shots for reflection seismic survey should be located at a minimum depth of 9.6m in the area to eliminate the effects associated with the low velocity layer.
ISSN:0016-7622
0974-6889
DOI:10.1007/s12594-017-0698-4