Cementation Factor Effect on Calculated Porosity and Water Saturation

The Cementation factor (m) has an important role in the calculation of hydrocarbon/water saturations from electrical wireline logs. Cementation factor is determined by laboratory data. This is done by performing laboratory measurements on core plugs obtained during a drilling job. However, often these laboratory measurements are not available. In this study a series of sensitivity tests were carried out for a carbonate reservoir containing oil, in order to assess the relative impact of cementation factor (m) on log-derived porosity and water saturation. It is concluded that calculated water saturation increases with increasing cementation factor especially in low porosity rocks. Therefore, special care must be taken when dealing with low porosity carbonate rocks as water saturation is extremely sensitive to cementation factor.