Anomalous self potential (sp) log signatures observed in a water well at Okwudor, South- eastern Nigeria

Abstract

Geophysical logging was done after drilling had been completed in a water well at Okwudor, South Eastern Nigeria. Three electric logs were run viz: Self Potential (SP), Resistivity N16″ and N64″ logs. An anomaly was observed in the SP log. The SP results from this well show some deviation from the standard norm. The zone indicated to be impermeable according to SP data contradicts the results of the two resistivity logs. The well was completed using resistivity data and litho log. The project became successful. Attempts are made in this paper to explain the probable cause / source of this anomaly in the SP signatures.

Keywords: Self potentials, resistivity logs, mud filtrate, anomaly, impermeable bed.

Nigerian Journal of Physics Vol. 19 (1) 2007: pp. 97-106