Relation of unconformity with hydrocarbon accumulation in Luxi area of Junggar Basin

The unconformity type and control oil characteristics, unconformity structural type and oil-gas migration-accumulation characteristics, evidence of oil-gas migration along unconformity surface and the hydrocarbon accumulation patterns of unconformity-fault migration-accumulation system in Luxi area of Junggar Basin were discussed. There are four types of unconformity including onlap-erosional truncation type, onlap-concordance type, concordance-erosional truncation type, concordance-concordance type. The onlap-erosional truncation type and concordance-erosional truncation type are the most favorable for oil and gas accumulation. There are six types of structural layers of unconformity. Among them, the type I and type II are the most favorable for oil-gas migration and accumulation. The migration of oil and gas at top boundary unconformity of all strata of the Permian system and the Triassic system only existed in the slope of Luxi area. The migration of oil and gas at top boundary unconformity of Xishanyao Formation and Jurassic system mostly existed in the uplift of Luxi area. There are two reservoir patterns including side of source-unconformity-slope-zone type and outside of source- unconformity-fault control-steps type in Luxi area. The favorable objects of reservoir in the stratum relative with unconformity include the slope of Luxi area, the jointing area of Sangequan Oilfield and Shinan Oilfield, and the southern member of Shannan Depression in Junggar Basin.