ESTIMATION OF AQUFER TRANSMISSIVITY FOR TYPICAL OIL PRODUCING COMMUNITIES OF WESTERN NIGER DELTA USING ELECTRICAL RESISTIVITY SURVEY

Abstract

Geophysical electrical resistivity method (Vertical Electrical Sounding) using Schlumberger configuration was employed to investigate subsurface formations and aquifer transmisivity in Agbarotor, Agbarha-Otor and Edoiede Agbarha-Otor in Ughelli North Local Government Area in Delta State, Southern Nigeria with VES evenly carried out in the aforementioned study areas. ABEM Signal averaging system (SAS) 1000 Terrameter, was one of the major equipments used in obtaining the resistivity field data with a maximum current electrodes spreading of 500m done with the aid of a tape. The interpretation of the data gotten from the field was done using WINRESIST software coupled with the qualitative and quantitative curve matching to obtain modelize parameters and curves type for various VES points. The model parameters displayed up to six formations layers which include topsoil, laterite, clay and sand (fine, medium and coarse) formation. The resistivity of the confined aquifer ranges from 1037.6-4986.5Ωm with thickness varying interval of 16.3m and 42.9m. The investigation denote that VES 1 of Agbarotor, VES 6 for Agbarha-Otor and VES 7,9,10 of Edoiede Agbarha-Otor are the best locations for citing boreholes in the studied areas since they are characterize with higher resistivity (low corrosivity) and moderate or higher transmisivity. Thus aquifer transmisivity in the cited areas are of good quality and the produce can sustain the people of the areas and neighboring environs for long period of time. I recommend that the samples of VES water locations should be tested from time to time to ascertain its Level of contaminations for future remedial measure and a water system for the general public should be drilled in the aforementioned VES points.