Abstract: Wuerxun-Beier Sag is the major hydrocarbon discovery area in Hailaer Basin, five major hydrocarbon accumulation belts have been found which reveals great exploration potential of the area. Research on hydrocarbon accumulation control factors shows that the distribution of effective source rocks, faults and favorable reservoir determine the location of hydrocarbon accumulation, hydrocarbon reservoirs mainly distribute within 10km from the effective source rocks center and within 1 km from the faults with a direction of NEE and NNE; siltstone and sandy conglomerate are the most favorable reservoir rocks, fan delta front is the favorable sedimentary facies. Considering that almost all the traps are related with faults, four kinds of fault-related traps are classified. Based on the study on main control factors, which are mentioned above, a multiple-factor superposition forecasting method is put forward, that is, the area containing all the favorable hydrocarbon accumulation conditions is the most favorable exploration area, and by using this method, the favorable hydrocarbon accumulation area of K₁n₂ formation is figured out, and 10 favorable targets of K₁n₂ formation are selected for next exploration by analyzing the sealing ability of the faults which control the boundary of the fault-related traps.

Key words: Hailaer Basin, Wuerxun-Beier Sag, main control factors, exploration target, trap evaluation