Middle Yangzi River Region,located in the middle part of Yangzi paraplatform,un-derwent three sedimentary evolution and development stages:basement formation stage;platform development stage and post-platform reformation stage.Sediments from Upper Sinian to Middle Triassic are mainly marine carbonate rocks of six to ten km thick.The sediments,with multiple source sequences,thick source rocks,type-Ⅰ kerogen as the major parent material,matured or high-matured organic matter,possess good hydrocarbon generating condition.The reservoirs,including mainly porous dolomite reservoir,paleo-weathered crust reservoir,shallow-beach reservoir and fracture-solution pore reservoir,are variety in types and great in thickness.The cap rocks are wide spread in the study area.It is suggested that the area has fine source-ressrvoir-cap rock assemblage,and favourable conditions to form commercial oil and gas fields.According to the preservation condition,the study area can be divided into threetypes:1.Shizhu-Wanxian tectonic stable area;2.paulopost fault-subsided area in Jiang-han Plain and 3.folded-uplift area in West Hunan-West Hubei region.Among them,the Shizhu synclinoriun in Chuandong is most favourable for gas exploration,Dangyang and Chenhu synclinoria located in hinterland of Jianghan Plain have best oil prospects.
