International Science and Technology Journal

Petrophysical characteristics of the Waha Formation in Ralah oil field, Concession 6 of Sirte basin, have been evaluated through the analysis of well-logging data recorded for six exploratory and development wells. These records have been analyzed through utilizing some cross-plots and use their outputs for controlling the interactive petrophysics software (IP) in order to evaluate the lithological constituents and fluid saturation parameters. The litho-saturation cross-plot results indicated that the Upper Cretaceous Waha Formation is mainly oil-bearing with some water-bearing sand levels with thickness ranging from zero on the crests of the paleo topographic highs to over 45 m on their flanks. The evaluation reveals also that the lithological facies consists mainly of limestone with few shales. The limestone is predominantly of tan to white grain supported skeletal calcarenite. The lateral distribution of the petrophysical parameters portrays that the Waha Formation is a good reservoir rock and considered a major reservoir in the Ralah field.