Abstarct: Seismic exploration is one of the most important geophysical methods. It is devided into reflection and refraction seismology. Reflection seismology is widely used in petroleum exploration. This method will gives seismic sections for geological interpretation. Aim of the seismic data analysis is to make seismic section and define exploration well location. According to high drilling expences, proposing accurate well location is a critical issue. Conventional processing methods needs accurate velocity model for depth convertion. Any small error in velocity model will cause even up to handred meter displacement in reflectors maping. Therefore, obtaining accurate velocity model is so important in reflection data processing and interpretation. This velocity model is used to convert time migrated section into depth sedction. This depth section is so important to define the well path in the subsurface laxyers. Depth counor map that used for this purpose is obtained by velocity model and migrated sections. These maps are used to locate probable oil traps. Therefore, velocity model has an important role in changing shape of the countor maps; it would increase in areas with complex structures and strong velocity changes. In this study, different horizons, Lafan, Ilam, Sarvak and Kazhdumi were picked from seven time migrated section in one of the oil filed from south west of Iran. These picked horizons were used to make structural countor maps. Different attributes were used for picking evaluation. These attributes proved accuracy of hand picking. Then well head information was used for depth convertion. Afterwards, Lafan, Sarvak and Daryan countour maps converted to depth maps by different velocity models. According to the closures in the countor maps, probable locations of the oil traps were defined.