Abstract: Fracture is the most important controlling factor for fault-block reservoirs. So clarifying fault system development characteristics and its sealing properties is a key step in fault-block reservoirs’exploration and development and favorable zones prediction. Many methods have been used to deal with the dome structure in Dongying Sag, such as the detailed interpretation of three-dimensional seismic data, the coherence cube analysis,and the fault activity analysis techniques. Based on those processing methods, the fault system spatial characteristics and its evolution of the study area were analyzed. Combined with the single factor analysis and comprehensive fuzzy evaluation, the sealing properties of the main faults in work area were analyzed. Based on all the above, the relationship between hydrocarbon accumulation and distribution and the fault sealing was discussed. The results show that, the Dongying dome structure originated from the upwarp of salt gypsum and plastic mudstone in Kongdian and the fourth member of the Shahejie formation, the reverse drag of the northern boundary fault and the latter dextral transtension and then was complicated by multi-stage superimposition, multi-directional trending and multi-type array fault systems. The sealing properties of different strata and different parts of the faults show difference. As a whole, in the third to the lower second member of the Shahejie formation, the sealing properties of the second-grade faults were quite good, but those of the third-grade faults were not so good. While in the upper second member of the Shehejie to the Dongying formation, the study of the sealing properties of these faults show that there is a good correlation between fault sealing properties and the reservoirs accumulation and distribution, that is, reservoirs are usually located by the faults with good sealing properties.

Key words: fault system characteristics, fault sealing, hydrocarbon accumulation and distribution, Dongying dome structure