Structural Control For Bitumen Seepages in Imeri, Southwestern Nigeria

Electrical resistivity survey was done to investigate the role of fault as barrier or conduit for bitumen seepages found in Imeri, S outhwestern Nigeria. Two (2) Vertical electrical sounding (1D) with a maximum electrode spacing(AB) of 700m using schlumberger array, and an electrical resistivity imaging (ERI) along the same profile using wenner array were used in this research work; the results we re interpreted using WINKLINK and DIPROWIN respectively. The bitumen horizon was encountered at depth of ~34.56m an d ~20.99m with resistivity value of 2206 and 4398Ωm in VES 1 and 2. The resultant lithological logs shows that layers are displaced relative to one another, with younger lithological units placed on top of older ones, this suggests the presence of a Normal fault; the fault has an estimated throw of ~28.1m. The 2D survey did not probe as deep as the VES but the result identified the bitumen horizon and possible fault zones. The bitumen seepages in Imeri were influenced by the presence of a fault and absence of a good cap rock. The fault is thought to serve as a conduit for the migration of the bitumen to the surface. Further fault seal analyses may incorporate the determination of the S hale Gouge Ratio (S GR) along the fault zones.