Electrical Resistivity imaging was conducted in a crude oil spill site at Obuguru in the Forcados estuary area of the western Niger Delta with the aim of investigating the lateral and vertical spread of the hydrocarbon. Five survey profiles were laid in the study area with three of them within the polluted area to map the contaminated zone. The 2D resistivity imaging technique using the dipole- dipole array method was adopted for the survey with the aid of the SAS 4000 Terrameter. The inferred lithology from 2D resistivity inversion are topsoil, clayey sand and sand. The inverted resistivity model shows variation of resistivity values ranging from about 0.95 to 64.2 Wm. The top soil has resistivity values ranging from about 1.52 to 64.2 Wm while the second, third and fourth inverted layers have resistivity values varying from 1.86 to 9.20 Wm. The sandy layers vary in thickness vary 1.5 – 8.5 m. The low resistivity values (1.86 – 4.9 Wm) are as a result of the salinity of the area. While the high resistivity values (6.7 – 17.6 Wm) are as a result of the presence of hydrocarbon. The lateral extent of hydrocarbon pollution on this profile is about 27m while the vertical penetration is approximately 3m. The 2D sections were merged to form reasonably accurate images of 3D structures. The volume of contaminated aquifer matrix was estimated to be approximately1200 m3.
