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Determination of the Physical Properties of Near Surface Layers of Omerulu Area, Nigeria, Using Seismic Refraction Method
International Journal of Oil, Gas and Coal Engineering
Volume 5, Issue 5, September 2017, Pages: 97-115
Received: Apr. 5, 2017; Accepted: Apr. 20, 2017; Published: Oct. 24, 2017
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Authors
Olowofela Joseph Adeniyi, Department of Physics, Federal University of Agriculture (FUNAAB), Abeokuta, Nigeria
Akinyemi Olukayode Dewunmi, Department of Physics, Federal University of Agriculture (FUNAAB), Abeokuta, Nigeria
Odumosu Olutayo, Exploration Unit, United Geophysical Company, Warri, Nigeria
Ajani Olumide Oyewale, Department of Physics and Solar Energy, Bowen University, Iwo, Nigeria
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Abstract
Seismic refraction method is a geophysical technique used to study physical properties of the subsurface such as layer thicknesses, travel times and velocities of seismic signals through the layers. The process of turning seismic refraction data to useful information involves use of first arrival times and offsets. In this study, the near surface investigation of the physical properties of the unconsolidated and consolidated layers was carried out in Omerelu, Rivers State of Nigeria. Omerelu lies between latitude 050 08’N and 050 13’N and longitude 060 51’E and 060 58’E. Previous investigations were based on refection method in which the near surface effect caused misalignment in the deeper horizons observed in the final stack of the reflection data. This problem was solved by running a seismic refraction survey over the area. The study involved identification of points at which data would be acquired to give a good overview of the area under consideration. Twelve sampling points were picked with a grid of approximately 4 × 4 km. A 100 m line with two source points at each end was cleared at each data acquisition point after which the coordinates were taken using Leica Total station (TC 1203 survey equipment). Seismic signals were recorded using OYO McSeis 160M coupled with a 12-geophone harness along with a blasting unit. Upsphere processing software was used to plot time - offset graphs to determine the velocities of the unconsolidated and consolidated layers. The intercept times were also graphically obtained and used to determine the thickness of the unconsolidated layer. Results show that the thickness of unconsolidated/weathered layer in the study area varies between 12.25 and 13.60 m, while the velocities of the unconsolidated and the consolidated layers vary between 500 – 550 m/s and 1790 – 1875 m/s respectively. The results obtained when applied to the reflection data, were able to resolve the static problems; thereby increasing and improving the quality of data available on the lithology of the study area.
Keywords
Arrival Times, Offsets, Misalignment, Intercept Time, Seismic Refraction Data, Consolidated Layers, Unconsolidated Layers
To cite this article
Olowofela Joseph Adeniyi, Akinyemi Olukayode Dewunmi, Odumosu Olutayo, Ajani Olumide Oyewale, Determination of the Physical Properties of Near Surface Layers of Omerulu Area, Nigeria, Using Seismic Refraction Method, International Journal of Oil, Gas and Coal Engineering. Vol. 5, No. 5, 2017, pp. 97-115. doi: 10.11648/j.ogce.20170505.15
Copyright
Copyright © 2017 Authors retain the copyright of this article.
This article is an open access article distributed under the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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