Cross Plot And Contour Closure Evaluation Of Resistive Zones For Groundwater Exploration In Parts Of Emuoha Local Government Area, Rivers State

Abstract

Accelerated urbanization in Emuoha Local Government Area has escalated groundwater demand, yet borehole development remains challenged by intense lithological heterogeneity within the Tertiary Benin Formation. To eliminate geoelectric structural ambiguities that lead to dry holes, this study integrated conventional one-dimensional (1D) Vertical Electrical Sounding (VES) cross-plot analysis with high-resolution two-dimensional (2D) Advanced Digital Magnetic Tomography (ADMT) profiling. Using the Schlumberger array configuration, field data were acquired up to a maximum current electrode separation (AB/2) of 100m and inverted using computer-aided modeling. The 1D VES results resolved a four-layer, HK-type with the trend ⍴1>⍴2<⍴3>⍴4, identifying a massive, clean, and highly resistive sand reservoir. Cross-validating these layers, the 2D ADMT tomograms mapped continuous, distinct low-resistivity contour closures that confirm prolific water-bearing channels at depths, alongside a secondary deep, high-pressure confined horizon at 110m. These closed contour signatures indicate optimized porosity, high transmissivity, and excellent fluid saturation shielded from surface contamination. This paper contributes a novel, field-verified predictive geophysical model that establishes a robust exploration template for sedimentary basins. Based on these findings, it is recommended that regional drilling operations prioritize targeting the deep, continuous 110 m contour closures to secure sustainable, maximum yield production and minimize borehole failure rates across the Niger Delta.