Porosity analysis is the way to have a better understanding of porosity system in oil and gas fields. By using the image log technology, we can do this analysis verywell, but this process is complicated and it is still unknown to many researchers. Therefore, we decided to explain this process by using a unique case study and a number of valuableimage log interpretation examples. This jobwill be done for two wells (GS-A & GS-B) located inGachsaran field, one of the most important Iranian fields, and the main reservoir that will be studied isAsmari reservoir, one of the most important Iranian oil and gas reservoirs. We aim to offer a unique educational paper that will be very useful for the other researchers who are interested in image log technology.