Abstract:

The sealing property of faults is affected by the combining manner between the maximum principal compressive stress orientation of tectonic stress field and the strike direction of faults at the same stage．When the acute angles of them are larger，the sealing properties of faults are better. If the acute angles of them are smaller，the sealing properties of faults are poorer，the liquid permeability in fault is better and good for the liquid migration. For the reasons given above，we can appraise the sealing property of fault semi-quantitatively used the sealing coefficient calculated by the method of liner algebra．By analyzing the evolving history of the sealing property of faults in the different stages of petroleum migration,the advantaged parts，which can gather oil and gas，are forecasted in some fault zones. By evaluating to the Bohai Bay area synthetically，lt is recognized that the petroleum gathering of fault depressions at east-west or north-south trending are the best，and the parts areas of the northeastward  or northwestward of fault depressions，sometimes are well for petroleum enrichment．Miaoxi-1 fault，Kenli-3 fault and Miaoxi-3 fault are forecasted for beneficial fault depression zones of petroleum exploration in the future．

Key words: fault zone, sealing property, tectonic stress, petroleum accumulation, Bohai Bay