Middle and Lower Triassic sedimentary facies within the Urho uplift on the northwestern margin of the Junggar Basin

The Baikouquan and Karamay Formations within the Urho uplift on the northwestern margin of the Junggar Basin are composed dominantly of glutenite, conglomerate and sandy conglomerate, with subordinate sandstone and mudstone based on the cores, thin sections and well logs. The hydrocarbon reservoirs in this area are dominated by the low-porosity and low-permeability reservoirs, locally by the moderate-porosity and moderate-permeability reservoirs in the Karamay Formation. The principal source of detritus lay to the areas west to the Huangyangquan in the west, and Hala'alate Mountains in the north. The alluvial fan deposits in the Baikouquan Formation and fan delta deposits in the Karamay Formation constitute the excellent hydrocarbon reservoirs in the study area.