The paper describes the developed method called “modified reservoir quality map ”. The paper includes the theoretical base of the method, the methodology for quality map construction and mathematical operations over the map. Definitions for well and well network qualities are presented. The work includes a description of the working principle of our developed software for mapping the quality of the reservoir. Finally, the results of applying the method for three fields with examples of wells (that are in “good” and “bad” zones) are presented.