Near-Surface Geophysical Survey for Pipeline Route Selection in Ogun State, South West Nigeria

Route selection for buried petroleum pipelines requires detailed subsurface characterisation to identify geotechnical hazards, crossing complexities, and corrosion-prone zones that affect construction cost and long-term pipeline integrity. This study applies ground-penetrating radar and electrical resistivity profiling along three candidate pipeline route corridors in Ogun State to provide comparative geophysical risk assessments. GPR data were acquired along the entire 12-kilometre length of each candidate route using a 250 MHz antenna at walking pace, providing continuous subsurface imaging to depths of 3 to 5 metres. Electrical resistivity profiles were acquired at 1-kilometre intervals along each route to characterise subsurface conditions at greater depths relevant to pipe burial. GPR profiles reveal differences in the frequency and extent of buried utilities, rocky outcrops, and waterlogged zones between routes. Route A encounters the fewest subsurface anomalies and has the most uniform soil profile, whereas Route C shows numerous hyperbolic anomalies interpreted as buried utilities and rocky protrusions requiring extensive blasting. Corrosion risk zoning based on soil resistivity values identifies a 1.5-kilometre section on Route B characterised by resistivities below 10 ohm-metres where impressed current cathodic protection measures would be mandatory. The study recommends Route A as the preferred alignment and provides subsurface characterisation data for detailed engineering design. Keywords: pipeline route selection, GPR, resistivity, Ogun State, corrosion risk