Abstract: Changshaling structural belt, located in west slope of lake basin in Ying’er sag, is a large-scale nose-like uplift shaped by a series of complex faults, and the main hydrocarbon-bearing sequence in it is in Chijingbao formation of Lower Cretaceous. The formation of structural belt underwent such three stages as tensional block faulting in the early of Early Cretaceous,compaction folding of S-N direction in Middle-Late Cretaceous and reconstructing and shaping in Tertiary.Dark shale is well developed in the lower section of Chijingbao formation.Sandstone is mostly found in the upper section of it.Faults are the major channels for connecting source rocks and reservoir rocks. And its primary type of reservoir-cap rock assemblage is source bed in lower formation and reservoir bed in upper formations.Many prospecting wells have been penetrated in sandstone layers of Chijingbao formation on the structural belt and obtained oil-gas flow. Hence, superior petroleum geological conditions allow this structural belt to become one of key exploratory areas in Y umen oilfield in the near future.

Key words: Jiuquan basin, Ying'er sag, block faulting movement, source rock, reservoir rock, cap rock, hydrocarbon potential