Deep Basin Gas Accumulation in the Upper Triassic of Chuxiong Basin

Depositional settings of the upper Triassic of Chuxiong basin are favorable for the deep basin gas accumulation. The fluvial and deltaic deposits constitute the dominated reservoir in the deep basin. The numerous and mature coal beds and organic-rich shales associated intimately with reservoir rocks throughout the deep basin provide a prerequisite for deep basin gas accumulation. Gas has the tendency to be trapped in the deepest part of the basin and probably occupies low permeability reservoirs extensively. Gas generated in source rocks, moved into the adjacent sand layer and then slowly migrated updip. The filling process of deep basin gas lasted from the late Cretaceous to mid-Tertiary time. Gas may be located downdip of an aquifer which outcrops in basin margins. The gas accumulation of the upper Triassic of Chuxiong basin is predicted and interpreted based on the trapping mechanism of deep basin gas reservoir. The distribution of deep basin gas accumulation in the basin is described according to the key parameters controlling the ultimate trapping.