Combination of Core and Log Data for the Prediction of Compressional Wave Velocities in Carbonate Rocks

The relation between compressional wave velocity and porosity depends on porosity, porosity type, mineralogy, saturation, and pressure in carbonate rock. Therefore, data points are scattered in a velocity-porosity cross plot. In this study, two methods of rock typing in carbonate rocks are analyzed to investigate the relation between compressional wave velocity and porosity. For this purpose, flow zone indicators and velocity deviation values are used. Flow zone indicators are determined from differences between sonic velocity and the velocity obtained from Wyllie time average equation using neutron porosity. The results show four hydraulic flow units with flow zone indicators from 2.23 to 19.95 and four rock types based on velocity deviation values from 139 to 1135 (m/s). Moreover, the results show that the rock typing based on velocity deviation values is more accurate than that obtained by flow zone indicators. The average value of correlation coefficient is 95% for grouping based on velocity deviation values, whereas this value is 67% for grouping based on flow zone indicators.