There many methods for estimation of permeability. In this Paper, permeability has been estimated by two methods. The conventional and modified methods are used to calculate flow zone indicator (FZI). The hydraulic flow unit (HU) was identified by FZI technique. This technique is effective in predicting the permeability in un-cored intervals/wells. HU is related with FZI and rock quality index (RQI). All available cores from 7 wells (Su -4, Su -5, Su -7, Su -8, Su -9, Su -12, and Su -14) were used to be database for HU classification. The plot of probability cumulative of FZI is used. The plot of core-derived probability FZI for both modified and conventional method which indicates 4 Hu (A, B, C and D) for Nahr Umr formation based on the four straight lines. The permeability was calculated by two methods for comparison and choosing the best. The modified FZI method gives better results because the predicted permeability by this method demonstrates a coefficient of correlation (R2) higher than that of the conventional approach, where the value of R2 is 0.9645 of modified FZI method while 0.892 of the conventional approach. When plotting RQI versus on a log-log scale, all core samples with similar FZI values will lie on a straight line with a unit slope. Other core samples that have different FZI values will lie on other parallel lines. All lines in (RQI and ) plot of modified FZI method have unit slop and more parallel than these of the conventional approach. The plot of probability cumulative of FZIm is used to determine number of hydraulic flow unit for Nahr Umr formation. The plot of core-derived probability FZI for both modified and conventional method which indicates 4 Hus for Nahr Umr formation based on the four straight lines, these four straight lines of modified FZI method was more distinguished than these of the conventional approach.
