Measurement of Archie Parameters of Some Carbonate Cores at Full Reservoir Conditions (Short Communication)

Application of Archie equation in carbonate reservoirs is not easy due to high dependence of its parameters on carbonate characteristics. Carbonates are very heterogeneous in nature and hydrocarbon reserve estimation in these reservoirs of mostly oil-wet and intermediate-wet is highly influenced by the input values of saturation exponent. To our knowledge, non representative oils have been used in most saturation exponent measurements and not many cases have used live oil for carbonate cores at full reservoir conditions. Performing these experiments at laboratory conditions which differs from reservoir ones would not yield reliable results. The main effort of this study was to properly measure saturation exponent on some carbonate core plugs of an Iranian reservoir at reservoir conditions using live oil by porous plate technique. Resistivity index and capillary pressure by drainage process on some plugs from pay-zone and resistivity index by imbibition process on some plugs from near and within transition zone of studied reservoir were measured. Regression fits by using Archie equation were not satisfying. Hence, the regressions were also obtained without taking into account the origin point which insisted the use of a “b” (saturation distribution) factor in the Archie equation.