Abstract Core samples from the main pay horizon of six Bombay High wells in India have been studied for the purpose of establishing relationships between logging and reservoir parameters. During this study porosity, permeability, bulk density, formation factor, saturation exponent, sonic transit time, cation exchange capacity, and insoluble residue content were determined under ambient pressure and temperature conditions. Meaningful relationships were established between different parameters that can be used for improved formation/ evaluation from well logs and for a better understanding of carbonate reservoir rocks. The most important findings of the present work are: (1) porosity is basically controlled by shaliness; (2) the formation may have very low permeability (< 1 md) and hence a poor hydrocarbon productivity when porosity is less than about 17 percent; and (3) the saturation exponent that is used in the computation of in situ oil saturation depends greatly on the formation shaliness.