The structural significance of seismic velocity reversals - an overview

The basic property under investigation is the change of seismic velocity from one layer to the other. This paper looks into problems of velocity reversal, locations of low velocity zones, delineation methods, and presents case studies in the Niger Delta. This study therefore aims at delineating from the surface the subsurface distribution of velocity changes in the area of study. It has been recognised in the study area that seismic velocity contains important geological information. To be most effective determining these, however, it is necessary to have a thorough understanding of the rock properties under investigation. In areas with absence of structural uplift and lateral variation of lithology, iso-velocity surfaces are nearly horizontal planes. However, where structural uplift occurs, iso-velocity surfaces tend to follow structure but less relief than the structure. The study showed that seismic velocity increases with depth and age in some of the areas and deviation from this was observed within the geopressured shales. These low velocity zones constitute anomalies that are not only geophysically significant but have structural definition. Keywords: seismic velocity reversals, Niger Delta Nigeria Journal of Pure and Applied Physics Vol. 4(1) 2005: 75-8

Stratrigraphy, facies distribution and depositional history of the Niger Delta shelf margin

No Abstract.Journal of Mining and Geology Vol. 44 (1) 2008: pp. 57-7

Elastic-wave and related properties of clastic rocks from a part of Niger Delta, Nigeria

Elastic-wave velocities of drill-core specimens with mineral compositions and textures of elastic rocks at Niger Delta, Nigeria, can be useful for identifying large zones of high porosity or high clay content (such as some fault zones, or the clay-rich haloes surrounding known uranium ore bodies). The overall objective of this study is to identify zones of high porosity and high clay contents using elastic-wave velocities Vp and Vs, and the ratio Vp/Vs. Thin sections were studied, and measurement of Vp, Vs, and porosity were made from cylindrical core specimens representing the Niger Delta Agbada Formation. Multiple linear regression has been employed to determine 1\Vp and 1\Vs, and the ratio Vp/Vs as a function of porosity (Φ) and clay fraction (Fc) for all specimen from the study area. The seismic velocities Vp and Vs, and the ratio Vp/Vs for Agbada sediment are found to be influenced by changes in porosity more strongly than by changes in clay content by a factor of approximately four. For clay fractions less than 0.15, simple linear relationships appear to exist between the reciprocal velocities 1/Vp and 1/Vs, and the ratio Vp/Vs, and porosity. Keywords: compressional, shear velocity, porosity, permeability, clastic rock Nigeria Journal of Pure and Applied Physics Vol. 4(1) 2005: 82-8

Seismic stratigraphy of part of continental margin, western offshore, Niger Delta

No Abstract.Journal of Mining and Geology Vol. 44 (1) 2008: pp. 83-9

Application of compaction trends in the prediction of porosity distributuion in 'Weden Field',Niger Delta

No Abstract

Application of travel-time inversion in velocity anisotropy estimation for lithology discrimination in some parts of the Niger Delta, Nigeria

No Abstract

Application of geophysical wireline logs in hydrocarbon reservior characterization: A case study from onshore Niger delta

No Abstract. Global Journal of Pure and Applied Sciences Vol. 12(3) 2006: 387-39