Application of velocity- deviation log to reservoir evaluation of Kangan Formation, South Pars Field
The velocity-deviation log, which is calculated by combining the sonic log with the neutron-porosity or density log, provides a tool to obtain the predominant pore type in carbonates. The log can be used to trace the distribution of diagenetic processes and to estimate trends in permeability. Laboratory measurements on carbonate samples reveal that sonic velocity is a function not only of the total porosity, but also of the predominant pore type. In general, there is an inverse porosity-velocity correlation, but significant derivations occur from this relationship for certain pore types. To produce velocity-deviation log, porosity logs were converted to synthetic velocity log using Wyllie equation. The difference between the real velocity calculated from sonic log and synthetic velocity calculated form porosity log, is defined as a velocity- deviation log. Using the deviation of this log to negative or positive values, the pore types are distinguished. This method performed for Kangan Formation in South Pars Field.