There are numerous oil fields in southeast Anatolia, near the northern extension of the Arabian Plate. The formations range from Cambrian to Miocene. Maturation and source rock potential of these formations are determined using reflectance and geochemistry. Tectonic features of these formations and oil reserves in the region are elaborated and oil generation is interpreted using these data. The maturity of rock units generally increases from west to east, while physical and chemical properties of oils also change accordingly. Oil reserves are generally located in east-west trending anticline systems in Cretaceous reservoirs. The API gravities and the alkane content of oils increase toward the east, while asphaltene content decreases in the same direction. All geological and geochemical data leads us to interpret that the oil is most probably generated near the west border of districts IX and X and migrated to the east.