New understanding of sedimentary facies of Shawan Formation in Chunfeng Oilfield, Junggar Basin

The Chunfeng Oilfield locates in the northeast of the Chepaizi Uplift,the western margin of the Junggar Basin.The sedimentary environment,source direction and sedimentary facies of the Shawan Formation in the study area are still under discussion.Based on core observation,carrying out experiments of light/heavy mineral,grain size and trace element,combining with well logging facies,it has been concluded that,the first member of the Shawan Formation in the study area was deposited in a typical underwater sedimentary environment.Sandbodies migrated to basin center from northwest and southwest.Sedimentary microfacies mainly include subaqueous distributary channel of fan-delta front in the northwest,distributary channel and interdistributary bay of braided delta front which distribute from southwest to northeast,and a few beach-bar sandbodies parallel to coast in the west.