The presence of water in oil reservoir cores has been observed for several years by analysts using a direct method for fluid content determinations. The actual amount of water that is present in the sand is of importance in the estimation of oil reserves as well as in determining the type of fluid which a particular stratum will produce under conditions favorable for flow into the well. The core analysis profile of a well cored with oil (using Baker Core Barrel) is compared with three other wells which were cored with water. The analysis of the former core is in close agreement with respect to oil and water saturations, 30.58%, 44.40% respectively, with other cores in the area, and points to the conclusion that water was distributed throughout the sand section with no indication of gravitational separation at the time of coring. Coring with oil or the addition of indicators to the fluid used during coring and the subsequent analysis of same are methods for determining correct interstitial water saturation.