oa Investigation and Model Correlations of Vp/vs and Porosity of Carbonates

Many articles deal with the topic of compressional and shear wave velocity of carbonate rocks and their correlation as well as model correlations. This paper will show the first results of compressional and shear wave velocity measurements and the calculations using the model of Kuster & Toksoez. Different carbonates of Austria were measured in the laboratory to determine their porosity as well as their compressional and shear wave velocity (dry). Two different measurements were executed to determine the effective porosity of samples (helium porosity and principle of Archimedes). Some samples have bigger helium porosity than the porosity that derived using the buoyance method. It was assumed that there are more pores with a radius under the radius of a water molecule, while they are big enough to let a helium molecule through.

Using the measured compressional/shear wave velocity and the effective porosity the inclusion model that developed by Kuster and Toksoez was accomplished for the dry samples. This model is limited to low porosity our result was sufficient. The penny shaped cracks with different aspect ratio (0.005–0.5) were used. It was observed, that different aspect ratios needed to be applied for different lithologies.