UPHOLE SEISMIC REFRACTION SURVEY FOR LOW VELOCITY LAYER DETERMINATION OVER YOM FIELD, SOUTH EAST NIGER DELTA

Abstract

The uphole refraction survey was carried out in ‘‘YOM’’ field 4-D prospect to evaluate the weathering thickness and velocity of the low velocity layer (LVL). Five uphole locations were occupied in the study area and the time – intercept technique of the seismic refraction interpretation was employed. For the different locations (A, B, C, D and E), the weathering thickness was found to vary from 0.9m to 1.9m with velocity from 250m/s to 800m/s. A sub weathering layer was also observed in all locations except A. Also, the velocity of the consolidated layer was found to vary from about 1750m/s to 1800m/s with a mean velocity of 1766m/s. Using this result to eliminate the effect of LVL on reflection data from the graphical approach, it was observed that the elevation and weathering correction (static correction) was found to be eliminated at a datum of 2m deep.