Correlation of Schlumberger Array Geoelectric Log with Borehole Lithologic Log in Ekiti State University Campus, Ado Ekiti, Ekiti State, Nigeria.

Abstract

Correlation of the schlumberger array geoelectric logs interpreted from Vertical Electrical Sounding (VES) data acquired in Ekiti State University Campus with borehole litholigic logs from the same area was done with the aim of establishing a mathematical relationship between the two logs. The study area is located within the basement complex of southwestern Nigeria, where occurrence of groundwater is limited to specific localized and enclosed regions within the weathered or fractured zones. Therefore, thorough geophysical surveys before drilling become necessary. The availability of borehole data in this area reduces the risk of data interpretation errors and enables prediction through statistical analysis. The Vertical Electrical Sounding data acquired from five stations within the campus were processed and interpreted using WINRESIST interpretation software. The results from the 2-D interpretation of the VES data were used to prepare five geoelectric sections which were compared with the borehole litholigic logs obtained from the same VES points using regression analysis. Depth to bedrock from Geoelectric log was correlated with the depth to bedrock from Lithologic log. The correlation coefficient gave a positive value of 0.9, which indicated a high degree of correlation between the geoelectric log and the borehole logs. The regression analysis equation obtained was y = 1.14x + 2.48. The equation is useful in converting the geoelectric logs to drilling logs in any location within the study area.