y sdalimi delshad - student of mine engineer at the school of mining
e kazemzadeh - assistant professor
a moradzadeh - associate professor at the school of mining

Irreducible water saturation is one of the most important parameters in evaluation of hydrocarbon reservoirs. For direct determination of it , the samples with preserved saturation are needed. In order to prepare these samples , we have to spend a lot of money and time , and sometimes getting sample is in not possible. in this article combination of experimental mercury capillary pressure data and rock calssification by hydraulic flow units are used for estimation of irreducible water saturation. the number of hydraulic flow units has been determined using lab measured porosity and permeability on the samples from one of the carbonate hydrocarbon reservoir. flow zone indicator for each sample is determined by calculation of reservoir quality index and normalized porosity , and then by drawing histogram and cluster analysis the numbers of hydraulic flow unit are calrified. the value of irreducible water saturation for each sample is obtained by mercury capillary pressure data that has been converted into reservoir condition. finally relationship between irreducible water saturation and reservoir quality index has been determined in each hydraulic flow units.

irreducible water saturation, hydraulic flow unit, capillary pressure , carbonate reservoir.