Subtle reservoir type and favorable exploration belts in Junggar Basin

According to the great potential and complicated accumulation rules of subtle reservoirs in the Junggar Basin, we divided the discovered subtle reservoirs in the study area into 4 types (lithologic, stratigraphic, complex and quasi-continuous ones) and 17 subtypes based on previous exploration experiences. The accumulation characteristics were concluded as followed: the control of multiple sedimentary systems; the occurrence of multiple trap types and the combination of structural-lithologic-stratigraphic traps; multiple hydrocarbon bearing layers; multiple stages of hydrocarbon charging and accumulation; multiple oil and gas plays. The favorable exploration belts of subtle reservoirs include the Shawan Formation in the Chepaizi slope in the western margin of the basin, the Jurassic around the Che-Mo paleo-uplift, the Carboniferous in the Junggar Basin, and the Jurassic tight sandstones in the piedmont depression of the North Tianshan.