Influence of Tectonic Activity on Reservoir Formation in the Bozhong34 Block
构造活动对渤中34区块油气成藏的影响

There are many tensional faults and strike-slip faults of different time and different strikes in the Bozhong34 block,the complex structural background makes the petroleum exploration difficult.In this paper,based on the interpretation of structure through seismic data as well as geological data,we discuss the evolution processes of tectonic activities and their influence on the petroleum accumulation.The results show as follows:①The depocenter dominated by tectonic activity controls the distribution of source rocks in the member 3 of Shahejie Group,lower segment of Dongying Group and lower segment of Minghuazhen Group,which deposited in the semideep-deep lacustrine facies environments.The subsidence and filling since neo-tectonic movement makes three sets of major source rocks be buried quickly and enter into hydrocarbon generation peak.②During a slow chasmic period to a quick depression period of Kongdian Group,a depression period of member 1 to 2 Shahejie Group,a diversion period of chasmic to a depression period of upper segment Dongying Group,and a thermal subsidence period after the second chasmic period of Guantao Group and lower segment of Minghuazhen Group,the reservoir sand bodies with different sedimentary faces were formed.The thick mudstone deposited during the thermal subsidence period after the second chasmic period is composed of a good cap.③Both anticlines formed by compression-torsion and drag structures done by tension-torsion are favorable of the formation of structure trap;the lenticular sands in the mudstone become a lithologic trap due to inter-fingering interlace between mudstones and channel sands.④There is a good match between hydrocarbon generation-expulsion period and Neogene fault activity,causing the improvement of effective migration and certain loss of petroleum.So the formation of good petroleum reservoir is required for the beneficial source-controlling conditions.⑤Faults with EW strike formed at late tectonic movement cut the early faults with NE strike and form the fault network,which links up the unconformities and make source beds connect with reservoir.the periodically active faults become the migration pathway of petroleum at active phase and act as sealing at passive phase.⑥There are two patterns of petroleum filling,one is that the petroleum migrates vertically through major faults which cut through source beds or "transfer station";the other is that petroleum migrates step by step along secondary faults and sands.