The reservoir that produces water at high structure and oil at low structure maybe present phenomenon of oil/water inversion in super-heavy oil reservoir in the lower member of Guantao Formation of Block Cheng911-Ping1，Chengdong Oilfield. Its reason is not clear yet. Based on the well logging，experiment and dynamic data of development，the characteristics of oil/water inversion and its genesis were analyzed comprehensively. The ground crude oil density ranges from 1.007 6 to 1.024 8 g/cm3，which is higher than the formation water density in this area. The heavy oil migrates to the lower structure against the buoyancy and capillary force under the action of gravity，and it is the main reason of the oil/water inversion. This viewpoint was confirmed by mud logging and well logging data. The oil/water distribution law in reservoirs featured by oil/water inversion is very different from that in the conventional oil reservoir. Some principles and methods for delineation of the oil-bearing area in the conventional oil reservoir are not applicable to reservoirs featured by oil/water inversion. Taking proven oil-bearing area as an example，the corresponding delineated principle and the key points in delineation of oil-bearing area in the super-heavy oil reservoirs were proposed aiming at the complex oil-water distribution.