Effects of petrophysical rock properties on tortuosity factor

Tortuosity factor is an important parameter of formation resistivity factor calculations in the Archie formula, which is used to predict water saturation. The objective of this work was to study the effects of petrophysical rock properties, i.e., amount of finegrains, porosity, cementation factor, formation resistivity factor, electrolyte concentrations and degree of brine saturation, on the tortuosity factor using Berea and synthetic sandstones cores. This study also trying to formulate empirical correlations between tortuosity factor and these studied petrophysical rock properties. The obtained results showed that the tortuosity factor is not a constant value, but it varies largely according to many parameters such as were studied in the present article. It was found that it increases as a result of decreasing the amount of fine grains, increasing formation resistivity factor, and cementation factor, and decreasing both porosity and degree of brine saturation. Tortuosity obtained from electrical resistivity measurements is very close to the tortuosity obtained from capillary pressure data. The analysis demonstrated that the correlations between the tortuosity factor and the petrophysical rock properties would yield a strong relationship with most accurate coefficients. (c) 2005 Elsevier B.V. All rights reserved.