Abstract: There are three types of fault depressions distributed in Hailaer Basin, i.e., mono-faulted depressions, double-faulted depressions, and fault depressions with bulging superposition in the center. Based on the comparative study on different types of fault depressions, it is regarded that continuously sedimentary subsags with big width and depth features in well-developed hydrocarbon source rocks and abundant oil resources. Favorable reservoirs may be composed of sandstones, conglomerates basement metamorphic buried hills, and volcanic rocks. There are three hydrocarbon generation and expulsion stages in the basin, and the crude oil is migrated laterally and vertically in it. 2~4 source-reservoir-cap assemblages and 12 types of oil and gas reservoirs develop based on favorable reservoir formation. Oil-bearing zones with different lithologic and structural features are easily to develop in the internal part or on the margin of subsags. Four oilfields have been discovered in the internal part or on the margin of the main subsags in Beir and Wuerxun fault depressions so far. It is therefore proposed in this paper to strengthen the exploration of such wide and deep subsags as Chagannuoer and Hongqi subsags, to lay emphasis on the exploration of superposed and residual fault depression, and to pay attention to the discovery of various oil and gas reservoirs including metamorphic buried hills, fracture slope breaks, and volcanic rocks, etc.

Key words: structural style, deep subsag, hydrocarbon source rock, comparative evaluation, oil-bearing model, Hailaer Basin