A Confined Fractured Basement Aquifer Research

This research involved theoretical modelling of a basement profile containing a confined fractured basement column with varying resistivity and thicknesses at different depths of burial. This was with a view to investigating the range of thicknesses and resistivity values for which the suppression prone confined fractured basement column is identifiable on the Vertical Electrical Sounding (VES) curve at different depth of burial. Several five-layer HKH-type theoretical Schlumberger VES curves for typical basement complex profiles containing the confined fractured basement column were generated while varying its thicknesses, resistivities and depth of burial. The results showed that the confined fractured basement columns were only detectable on the VES curve for thicknesses ranging from 10 m to 50 m and depths of burial ranging from 31 m to 201 m for resistivity reflection coefficient (k) values ranging from -0.92 to -0.56. None of the range of thickness ratios obtained for different thicknesses of the confined fractured basement column and depth of burial allowed for detectability on the VES curve for resistivity reflection coefficient values of -0.52, -0.47 and -0.43.