关键词: 乌尔逊凹陷, 层序地层, 沉积演化, 层序模式, 成藏条件

Abstract: The sedimentary history of Wuerxun Depression includes a few stages corresponding with structural evolution.The result of sequence stratigraphy research shows that the Cretaceous strata in this area involve two first-order sequences,five second-order sequences and twelve sequences.These sequences take on many obvious surface characteristics and abundant sedimentary systems.The sedimentary history includes two major growth cycles.The first cycle started from T₄,and the second cycle is a non-integrated cycle started from T₀₄.The general tectonic framework controls the form of the depression and the distribution of the depositional systems in the accommodation,which is the fundamental reservoir formation condition.Furthermore,the strata and the depositional systems are the essential physical reservoir formation condition.The major potential hydrocarbon resources are the dark mudstones of the condensed sections in sequence 4 and sequence 5 of second-order sequence Ⅱ and Ⅲ.The favorable reservoirs are mainly involved with lowstand fan,lowstand wedge,highstand delta front,highstand fan delta front and the turbidity fan in these two second-order sequences.

Key words: Wuerxun Depression, sequence stratigraphy, depositional evolution, sequence model, reservoir condition