Source-accumulation Migration System And Oil And Gas Distribution Of The Middle Triassic Lei-koupo Formation In Sichuan Basin

For further studying the differences of natural gas accumulation of Lei-koupo formation in Sichuan Basin,the author based on previous information,studying the Sichuan source rocks of different zones,migration unit,migration system,accumulation characteristics,revealing the differences of sources in different zones of the basin,the differences in migration conductors,the differences in migration systems and acculation,the research indicates that the oil and gas enrichment of the Lei-koupo Formation in the Sichuan Basin is controlled by the source-sink migration system.The analysis of natural gas composition,carbon and oxygen isotopes,hydrogen isotopes and inert gas isotopes in different gas reservoirs in the Lei-koupo Formation of the Sichuan Basin shows that the gas reservoirs in different zones of the Lei-koupo Formation in the Sichuan Basin are obvious difference.The T₂l⁴ gas reservoir in the Yuanba area of the northeastern Sichuan Basin is mainly derived from the source rocks of the Xujiahe Formation and the source rocks of the Lei-koupo Formation.The gas source of the Zhongba T₂l³gas reservoir in the northwestern Sichuan Basin is mainly from the Permian and below.The gas source of the Lei-koupo Formation gas reservoir in the Xiaoquan-Xinchang area of western Sichuan is derived from the source rocks of the Lei-koupo Formation,and the gas source of the T₂l¹ gas reservoir in the Chuanzhong Moxi from the hydrocarbon source of the Permian Longtan Formation.There are four types of migrations in the Lei-koupo Formation in the Sichuan Basin:faults and their fractured belt migrations,high-quality inside reservoir migrations in the Lei-koupo Formation,weathering shell migrations,and pleated associated seam migrations.Different migration conductors are combined with each other to construct a migration system from a hydrocarbon source to a trap?congruence?,that is,a source-sink migration system.Five types of source-sink transport systems developed in the Lei-koupo Formation of the Sichuan Basin:faults and fracture zones of the Lei-koupo Formation-external source-sink transport system,faults and fracture zones-folds,fault-related seams External source-sink migration system.The source-sink congruence system of the Lei-koupo Formation in the Sichuan Basin determines the reservoir model of the Lei-koupo Formation and controls the oil and gas enrichment of the Lei-koupo Formation in the Sichuan Basin.The Lei-koupo Formation in the Sichuan Basin is divided into four different oil and gas enrichment areas due to the different source-sink transport systems:the underlying faults and the fracture zone-your reservoir source-sink oil and gas accumulation zone in the concealed tectonic belt.Source weathering crust-excellent storage source-sink oil and gas accumulation area,underlying external fault fracture zone-associated fracture source-sink oil and gas accumulation area,slope with endogenous associated seam-excellent storage source-sink oil and gas accumulation area.