Abstract: Block Sagizski in the Pre-Caspian Basin is rich in hydrocarbon, and 20 oilfields have been discovered successively, all of which are located in the Post-Salt strata. This paper analyzed comprehensively the elementary geology, features of oil geology, oilfield distribution, and hydrocarbon accumulation conditions of this Block. The analysis revealed that the Middle Triassic and the Middle Jurassic were the main horizon of hydrocarbon accumulation vertically; the reservoirs were mainly distributed around the large oil windows horizontally. The oilfields discovered in early years concentrated in the west of Block Sagizski, most of which were the Middle Jurassic and the Lower Cretaceous reservoirs on the top of salt swell, while those discovered in recent years concentrated in the east of the Block and most of them were the Middle Triassic reservoirs. This paper also pointed out themiddle Triassic strata on the salt eaves (the shoulder of the salt swell) had favorable hydrocarbon accumulation conditions, and they would be favorable exploration targets in the future

Key words: regularity of hydrocarbon accumulation, Post-Salt strata, Block Sagizski, Pre-Caspian Basin