Abstract：The major logging methods employed to investigate the residual oil saturation in the cased hole include through-casing resistivity logging, carbon-oxygen ratio logging, neutral lifetime logging, neutral GR logging by injecting gadolinium into the reservoir and pulsed neutral-neutral logging (PNN). These residual oil saturation logging methods are reviewed in this paper, with the focus on their interpretation of field data, covering the working principle, geological applications and the technical capability of these methods. The latest developed through-casing resistivity logging tool by Russia, named as ECOS, enjoys many technical advantages in residual oil saturation calculation, hydrocarbon leakage zone evaluation, and reservoir management determination. As a relative mature technique, the carbon-oxygen ratio logging could be employed to calculate the oil saturation and the water salinity and to investigate the water flooded zones, as is more suitable for studies in the formation with low salinity and large saturation. The neutral lifetime logging is one of the most important methods to determine the residual oil saturation, but it is valuable just for perforated zones with medium or low salinity. Comparatively, the method of the neutral GR logging by injecting gadolinium into the reservoir is more useful for studies in the formation with low salinity.
2010, Vol. 28 
