Using statistical methods and information from petrophysical logs of eight wellbores, the porosity changes that are considered as important features to evaluate quality of reservoir were studied in the Asmari reservoir layer located in one of the fields of southwest Iran. Logs used to measure the porosity usually involve neutron and sonic logs. Normal distribution test, regression, and variance analysis are among the statistical processing methods suitable to examine changes in porosity with the depth of each wellbore and to compare these changes in the studied wellbores. The results showed that these processes are regarded as the fast and efficient ways for examining porosity in the fields with large area. Considering the results of tests conducted, it was determined that the porosity has not the same changes in the studied wellbores. Furthermore, it was determined that there is no particular trend between porosity and depth. This can be due to the dominant lithology type in the reservoir layer that is mostly the rock carbonate. These rocks are heterogeneous and their porosity are often secondary that was formed due to diagenesis and tectonic processes.

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