Velocity Analysis of 2-D Seismic Reflection Data

Abstract

This study is an attempt to estimate the seismic velocity structure of Umuta- Ogume prospect area in the Niger Delta from 2-D seismic reflection data acquired from the area. The line used in this study was a 15.00km strike line that cuts across rubber plantations, swampyfdry forests, farms and roads. A general discussion of procedures for acquiring and processing seismic reflection data is given. Under processing, emphasis was placed on the theoretical background to velocity analysis. An attempt was made to describe the particular procedure used in acqui&g the 2-D seismic data from Umutu-Ogume. These data were guided through the normal processing sequence including velocity analysis. The velocity analysis was done in two phases and the velocity values were obtained from the plots of velocity spectra and constant velocity stacks. The final velocity values were used in the migration of the seismic data. The migrated section was then interpreted. From stratigraphic interpretation of the migrated section and using the time-dept conversion formula established for the region, the thicknesses of the various formations of the Niger delta located within thc area were deteimined. Hence, the thicknesses of Benin and Agbada formations were estimated as 1,087:mand 3,097m respectively. The data suggest that the Akata formation starts from a depth of about 4,184m; the depth to the bottom of this formation could not be determined from the present data. The values of these thicknesses were compared with values obtained by previous workers in the region and were found to be in agreement. Some synthetic and antithetic faults were also identified by inspection of the migrated section.