Abstract:

Based on systematic analysis of 13 passive margin basins in South America, the authors conclude the characteristics of salt development: In plane, the salts mainly distributed in the middle 7 basins; In vertical, the salts developed at Cretaceous Aptian and migrated from north to south; There are 3 types of salt structures including unconformity type,conformity type and transitional type, 8 types of hydrocarbon traps. According to the planar distribution characteristics, the salt is formed in three mode, thin, transitional and thick mode. The development of salt controlled hydrocarbon accumulation in eastern area of South America: The plane distribution of salt controls hydrocarbon plane accumulation, the middle 7 salt developed basin accumulated more than 95% of the total hydrocarbon resource; The salt layer splits the basin into two parts in vertical, which formed post salt and presalt sets of hydrocarbon bearing reservoir. Hydrocarbon mainly accumulated in pre-salt formation in thick salt area while in post salt layers in thin and fierce change salt area due to the development of ‘salt window’; Salt related traps are the main hydrocarbon accumulation traps; The ‘salt window’ which formed by salt movement is the main pathway to connect lower source rock and upper reservoirs; Thick salt layer provides perfect sealing condition for pre-salt hydrocarbon accumulation.

Key words: South America, passive margin basin, salt structure, salt window, petroleum gas