Structural Characteristics And Its Controlling Effect On Hydrocarbon Accumulation Of Qingnan Sag

Qingnan sag,a typical rift lake basin,is one of the secondary structural units in Dongying depression.After drilled three exploration wells,there were 18-40 tons of oil production from the spray yield in 2012,Qingnan sag escalated into a hot exploration blocks in Dongying sag quickly.In this thesis,on the basis of three-dimensional seismic data,combined with well data,we made a refined study to the static characteristics of Qingnan sag fractures,and made it clear that how faults distributed,found out the evolution of faults.Then we analyzed the effect of the tectonic evolution on hydrocarbon accumulation,in the hope of providing guidance to future exploration.Qingnan sag mainly developed NW,EW and NE direction fault.As a result,extensional structural styles,strike-slip structural styles,slip-extensional structural styles were developed.In different geological periods,faults activated in different degrees,and its development process has apparent phase.Qingnan sag was in a NS extensional stress field during Kongdian formation-Sha four sector,and then was effected by dextral tenso-shear stress.Thus,the faults were activated,and NW direction faults were the strongest.In the end of Dongying formation,Qingnan sag uplifted,and during Neogene to Quaternary period,the whole sag depressed.The differences of tectonic evolution were in charge of stratum,reservoir and hydrocarbon migration and accumulation of Qingnan sag.The sag belt has a thin layer,and thus was the main area of hydrocarbon;sand-gravel bodies in the steep slope zone and bar sand in the sag belt was the main reservoir;faults in NW and EW directions were the main road of hydrocarbon migration;slip faults of NE direction were in charge of favorable.