Publications

Clastic reservoirs typically have a single porosity-permeability (poro-perm) transform based on grain size. Conversely, the complex depositional environments and diagenetic alteration present in carbonate reservoir systems result in complex pore structures, which results in a scatter of values in the poro-perm crossplot. A similar scatter exists in the porosity to acoustic velocity cross-plot, which becomes the key to classifying porosity - velocity groupings into separate poro-perm cross-plots. If the pore structure is known for each core plug in the scatter, the scatter can be segregated based on the pore structures. Then with log data only the pore structure can be determined by the porosity and sonic log relationships. Each of those pore structures will have a different flow behaviour. Digital Image Analysis (DIA) is a method to quantify pore structure parameters from thin section digital photographs. This method is faster, more accurate, and more repeatable in comparison to traditional carbonate rock types classification (for example Choquette and Pray classification, 1970) for characterizing pore structures. In this paper, the method has been applied to explain variations of acoustic velocity in meteorically leached limestones from a Dominican Republic outcrop. The Dominican Republic data indicates that permeability can be predicted by segregating the sonic velocity and porosity log relationships using pore structure information from the DIA analysis.