NEW COGNITION ON GENETIC MODEL OF JURASSIC SUBTLE RESERVOIR IN THE MXZ AREA OF THE HINTERLAND OF THE JUNGGAR BASIN

To establish the formation model of subtle reservoir in the MXZ area of the central Junggar Basin,after sequential analysis on core,well drilling/logging and seismic data,this paper integrated two sets of oil layers into the low-stand system tract of Sequence 1.Through follow-up investigation and research on this sequence boundary,it was detected that,in the vicinity of the slope break belt,tract sedimentary strata thickened with obvious foreset sand in the low-stand system tract,so oblique strata should be compared;in gentle terrains without the slope break,flat strata should be compared.Sequentially,formation mechanism of subtle trap is ascertained,and it is concluded that the change of base level is the main factor that controls the formation of subtle trap in the MXZ area.Based on that conclusion and the analysis on sand distribution,new formation model of subtle reservoir is summarized,i.e.,the plane is lobate,transverse section is lentoid,and longitudinal section is sphenoid with gentle slope.