Sedimentary Characteristics and Environmental Changes of Jurassic in Hongche Area,Junggar Basin

Jurassic in Hongche area is one of the important petroleum zones.The study on the sedimentary facies of Jurassic is a foundation work for exploration play.Based on microfacies of cores,also using the log information and seismic data,the main types of sedimentary facies of Jurassic in Hongche area have been indentified.They include alluvial fan,braid river,braid delta,lake,etc.Above all,the sandstone on the braided-river delta front and mudstone in shore-shallow lake are alternatively deposited on the oscillation background during the period of late Badaowan Formation and Sangonghe Formation which possesses the good source reservoir cap assemblages,hence they are the favorable facies zones for lithologic trap.Then the main seismic facies of Jurassic in Hongche area is studied;and on the basis of the analysis on middle basal level cycle,the planar distribution characters of sand groups are identified and the evolution history of Jurassic sedimentation in Hongche area is reconstructed.At last,the relationship between the sedimentary facies and lithologic trap is discussed and the favorable area for the Badaowan Formation and Sangonghe Formation sedimentary is pointed out.