| Popis: |
Summary Interpretation of log data with respect to porosity presents a complex task in carbonate rocks. In contrast to, for instance, clean sandstones, where a plot of the logarithm of formation factor F vs. logarithm of total porosity results in a straight line with the slope m (Archie, 1942), carbonates show a more complex behavior due to their intricate pore system. Archie’s equation is only valid for carbonates with connected interparticle pore space, whereas it fails if moldic or vuggy porosity not contributing to electrical conductivity are present. The aim of this study is to test a modified Archie equation with an exponent m* accounting for non-connected pore space by applying it to a set of samples with connected interparticle as well as nonconnected vuggy porosity. After verifying its validity, the approach is applied to log data to evaluate resistivity and porosity logs for effective porosity determination in a water-saturated carbonate formation. |
