Research Of The Fault Activity In He-31 Fault Block Area Of Dongying Sag

He 31 Fault Block of the Xianhezhuang oilfield is a typical high developed complex fault block reservoir. Under the influence of third graded faults, fourth graded faults and fifth graded faults, structure in fault block become very complex. Therefore, laws of fault activity, genetic mechanism of fault in He 31 Fault Block area needs further detail research. Basing on well logging and seismic data, guiding by the basic theory of structural geology,reservoir geology, sedimentology, using numerical simulation of stress field technology, on the basis of combine previous research achievements to explore the laws of fault activity,genetic mechanism of fault in He 31 Fault Block area in this thesis.He 31 Fault Block is Located in the middle of the western part of the central belt in the Dongying sag. It is a subsidiary positive structure element. On the plane,the trend of the fault in the study area is mainly NE-SW, Northeast convergence, Southwest open. On the profile, the fault generally tend to the Northwest dip, from south to north is down to form step-fault zone. The stratum is high in the north and low in the south. Angle is 8-13 degrees, forming the reverse roof with the fault. Dongying group and shahejie group are the main oil-bearing strata.Combined with analysis of fault activity, structure evolution history and actual data, that the faults in this region is divided into three level, third graded faults, fourth graded faults and fifth graded faults, the boundary of the fault block is mainly controlled by third graded faults. Fourth graded faults and fifth graded faults is derived from third graded faults, third graded faults formed in the shahejie period, fourth graded faults formed in the Dongying period.According to the analysis of structure evolution,fault active strength and fault growth index shows the formation period of the fault, combined with the regional tectonic setting and numerical simulation of stress field technology, geological model and mechanical model are built, get the results of the structural stress field numerical simulation of the end of the early tertiary in He 31 Fault Block area finally.The results shows that in the end of the early tertiary the high value area of the minimum principal stress and maximum and minimum principal stress differences are nearby He 125 Fault, which are concentrated areas of the low-level faults. Negative shear stress is distributed over the whole region, where the formation of NE-SW trending faults come out first. The section shear stress is dextral shear stress and easy to produce north treading faults. On the whole, the results of structural stress field numerical simulation of the end of the early tertiary agree well the results of fault interpretation of He 31 Fault Block.