Srata Sequence of Upper Jurassic in Lujiabao Sag

The Upper Jurassic in Lujiabao sag, the product inthe fault-subsiding period of rift basinporresponds to thesecond -grade sequence put forward by P.R.VRi1 and canbe divided into three sequence boundaries and twothird-grade sequences(A and B).Structure subsidence andPalaeogeographic background were the main controllingfactors of strata sequence in this region and constrainedthe development scale of each system traCt and thecharacteristics of depositional combination. Gequence AconsistS of low water level, lake extention and 1akecontraction system tracts where developed the maincombination of source rockpeservoir rock and cap rock inthis area.Sequence B only consistS of lake extention andlake contraction system tractS,the former is the regionalcap rock and secondary souree roch, and the later issecondary target for lacking regional cap rock eventhough there are high quality reservoir rock.