Trap styles and identification technology of concealed faults in Gaoyou sag

Key words:  concealed faults  trap styles  seismic coherence  Gaoyou sag

Abstract:

The formation mechanism and structural styles of concealed faults in Gaoyou sag of Subei Basin were discussed by using construction unit anatomy and physical simulations. The results show that there was a small angle between the NEE-trending basement faults and the regional stretching direction in the Paleogene period when the basement faults resurrected, of which there were four resurrection types, such as basement faults continuous disconnect type, en echelon normal fault type, connection fault type and discontinuous distribution stayed faulting type. The faults further evolved to concealed faults with different distribution characteristics and trap styles in the northern slope zone, Wubao fault zone and Zhenwu faulty zone of Gaoyou sag. Focusing on the characteristics of the concealed faults, the coherence technique which combines dip angle controlling, direction adjustment and filter method can effectively identify these concealed faults. The random survey line scanning technique is then used to implement fault occurrences. The application has been proven efficient in identifying many concealed fault block reservoir in Gaoyou sag.