Abstarct: Seismic waves amplitude is attenuated when passing through the ground laxyers. Descxription parameter of the attenuation is the quality factor that is used as an attribute that detects presence of hydrocarbons and fracturing in the reservoir. Purpose of this study is to investigate the distribution of quality factor in ASMARI reservoir that is a fields in the southwest of Iran. In order to calculate the quality factor log in each well, spectral ratio method using vertical seismic profiling is used that is conventional method to calculation of the quality factor. Since to obtain the vertical seismic profiling data is expensive, it is important to use a method for which the required data is more accessible. In this study, the quality factor is calculated with drift correction method that uses surface seismic data, sonic log and checkshot. To evaluation the drift correction method, its quality factor log is compared with that of spectral ratio method. Results show that the trend of both charts is highly similar. Then, the distribution of quality factor in reservoir ASMARI is estimates using stepwise regression. Resulting cross correlation and estimation error are 90.92% and 2.46% respectively. In order to improve the distribution quality factor, these results are used as an external attribute, and the process is iterated. At this step the cross correlation of 91.04% and estimation error of 2.06% are obtained.