Abstract: The studied results of regional geology, seismic, logging and core analysis data in the J₁b₁ sedimentary microfacies of the Badaowan formation in the Di-12 wellblock of Dishuiquan oilfield located in slope area of eastern Junggar basin show that the J1b1 is alluvial fan deposit, which could be further divided into 3 sub-facies of the top fan, middle fan, edge fan and 8 microfacies. The vertical variation of lithology and lithofaceies reflect that the target zone with the backfill characteristic on the Carboniferous is the earliest lowstand system tract of the Jurassic in this study area. The sedimentary environment of the J1b1 is transited from the top, middle fans up to the edge fan, showing such a period is in retrograding alluvial fan deposit under transgression environment. The identification of alluvial fan sedimentation microfacies of the Badaowan formation in Dishuiquan oilfield has a reference to prospecting the reservoirs related with the fans in eastern Junggar basin.

Key words: Junggar basin, Dishuiquan oilfield, Badaowan formation, retrograding alluvial fan, sedimentary microfacies