Using Log Clustering to Zone Fahliyan Limestone Formation Reservoir in One of Iran Southwest Reservoirs

Fahliyan limestone formation belongs to the Khami group, one of the oil and gas reservoir rocks in the southwest of Iran. This study is divided in two parts; in the first part, the reservoir characteristics of Fahliyan formation were evaluated in the well studied by taking into account the conditions of falling and gas effect on reading charts. Accordingly, lithology, by using neutron-density and M-N plots, was diagnosed to be limestone plus some mineral dolomite; the average of petrophysical parameters including effective porosity (PHIE), effective water saturation (SWE), and hydrocarbons in flashed zone and virgin zone were calculated to be 2.1, 56, 0.4, and 1.1% respectively. The pay zones and the average of petrophysical parameters in these zones by determining cut-offs for the two parameters of effective porosity (PHIE >= 2.2) and effective water saturation (SWE<= 55) were calculated. In the second part, the reservoir facies and non-reservoir facies were grouped by MRGC method and the sequence was partitioned into two reservoir and non-reservoir facies; the average of petrophysical parameters was compared between the two facies. There was good agreement between the specified reservoir facies and production zones in the total sequence evaluated. Finally, the reservoir main parts were identified for extracting gas and reservoir zoning was carried out in the interval studied.