Application of Resistivity Sounding in the Exploration for Nigerian Tarsand

Abstract

The extensive tarsand deposits of Ondo and Ogun States of Nigeria have previously been investigated only by the use of geological methods. In a recently completed exploration programme covering a 17 km2 area north of Agbabu, in the Ifesowapo Local Government area of Ondo State, the electrical resistivity technique was used extensively along with other exploration methods. The electrical resistivity survey was made up of 32 Schlumberger vertical electrical soundings (VES). The resistivity curves were interpreted by curve matching and computer based automatic interpretation techniques. Apparent resistivity values obtained varied between less than 10 ohm-m to greater than 1000 ohm-m. The results permitted fair to excellent correlation between the geoelectrical and Stratigraphic data, particularly the delineation of lithological boundaries and zone of bitumen saturation. The lithological boundaries and zone of bitumen saturation. The geophysical results also confirmed the regional block faulting and the consistent, increase in overburden thickness southwards.