Evolution of the paleostructure and its control on gas reservoir of Lower Permian Maokou Formation in northwest Sichuan
Using drilling,logging,core,field profile and seismic data,the paleostructure recovery and reservoir control of Permian Maokou Formation in northwest Sichuan during hydrocarbon accumlation period are studied.The research shows that platform margin shoal and intra-platform shoal are developed in Maokou Formation in northwest Sichuan,and Cambrian and Permian hydrocarbon sources are widely distributed in the area.The paleostructure of the top of Late Permian Maokou Formation is generally characterized by the"high in south and low in north"pattern,and a low uplift in NW-SE direction is developed.During the Early and Middle Triassic,the paleostructure was transformed into the"high in west and low in east"pattern,and a large area of paleostructural trap was formed in Jiange area.In the Early Jurassic,the paleostructural pattern was transformed into the"high in east and low in west"pattern,and the tectonic high point migrated eastward to Jiulongshan area.This paleostructural pattern was adjusted into a pattern of high margin and depression in the middle part of the basin after the Himalayan epoch.Fluid inclusion homogenization temperature analysis shows that there are four stages of oil and gas migration in Maokou Formation.Combining with regional hydrocarbon source evolution history,it is considered that the platform margin zone of Late Permian Maokou Formation is a favorable area for oil and gas migration.Paleo-traps in Jiange area formed in the Early and Middle Triassic can better capture oil and gas.In the Late Triassic,natural gas mainly migrated northeastward to the low-amplitude anticline traps formed in Jiange,Jiulongshan and Yuanba area,and further accumulated towards high parts during the Himalayan period,adjusting and forming the present gas reservoir.The platform margin zone of Jiange-Zhabachang has a good matching relationship with the hydrocarbon source and paleostructure,and has great gas reservoir exploration potential.
gas reservoirpaleostructureMaokou FormationLower Permiannorthwest SichuanSichuan Basin
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NSTL
万方数据
