At the time of this work, induction- and porosity-log measurements were available in more than 180,000 ft of hydrocarbon column from 428 wells. Water saturations were determined from this areally and vertically extensive database after calibration to oil-base-core (OBC)-derived water saturations. This paper presents the method used to calibrate the log data to the OBC water saturations and reviews the methods used to derive resistivity and formation factor values. It also presents field measurements of as-received core-plug resistivity and water-saturation values from two oil-base-mud (OEM)-cored wells. Comparisons are presented with both field water saturations and ＇＇routine＇＇ electrical-property measurements on extracted plugs.