The Characteristics Of Faults And Relations With Hydrocarbon Accumulations In The Liaodong Bay Of The Bohai Sea

The Liaodong Bay depression in the Bohai sea is rich in oil and gas resources.The Tan Lu fault zone runs through the Liaodong Bay area and plays an important role in its structural deformation and hydrocarbon accumulation.Based on the latest seismic data,through the methods of seismic data interpretation and balanced profile analysis,this paper studies the structure patterns,distribution characteristics and formation mechanism of the different types of faults,and their controls on hydrocarbon accumulation in Liaodong Bay area.Moreover,we summarizes the reservoir forming modes of typical oil and gas reservoirs in the study area,so as to provide reference for the future exploration.The results show that there are mainly shovel type,slope flat type,rake type,conjugate X-type and fault step belt of extensional fault systems,and positive flower,negative flower and mud diapir of strike slip fault systems in the Liaodong bay area.The distribution of different types of faults has obvious regularity in time and space: the extensional faults are mainly developed in the pre-Neogene,and their formation is controlled by the NW-SE extensional activities of the Bohai Bay basin in the Paleogene;the strike slip faults are obviously developed in the shallow layer,and mainly formed during the right strike slip activity of Neogene-Quaternary.The faults formed in different periods superimpose and transform each other,forming fault styles dominated by extensional faults and supplemented by strike slip faults and related structures.The abundant fault patterns in the Liaodong Bay area lead to the trap types are mainly fault anticline and fault block.The faults not only control the formation of hydrocarbon traps,but also control the distribution of sedimentary system.The fault terrace and structural transition zone formed source channel,and strike slip fault zone controls the migration of sedimentary center.Affected by this,the distribution range of sedimentary center in the study area is expanded,which is conducive to reservoir development.In addition,the faults also play an important role in hydrocarbon migration and accumulation in the Liaodong Bay area.The deep extensional fault system and shallow strike slip fault system provide favorable conditions for vertical migration and cross layer accumulation of hydrocarbon,and are also important transport channels connecting source rocks with lithology and buried hill traps in the Liaodong Bay area.