Abstract: The analysis of petroleum accumulation conditions of U pper Triassic Y anchang formation (Chang-2 to Chang-7 sand layer) in Chuankou-Qinghuabian area in Erdos Basin is made, on which the dynamic process of petroleum accumulation during the period of geologic history in this area is reconstructed by digital basin modeling. The result shows that porous sand body is the mainly conductive system of hydrocarbon migration, and the distribution and style of sands control diretly the site of oil-gas enrichment in this area. The early Cretaceous is its main petroleum accumulation stage for abnormal flowing pressure developed in Y anchang formation, predominant conductive nature of sands and proper configuration of petroleum accumulation dynamics and conductivity. Based on these, 3 models for the main petroleum migration and accumulation in Chuankou-Qinghuabian area, namely intimate source type, close source type and distal source type are developed in this paper.

Key words: Erdos basin, Qinhuanbian oilfield, Upper Triassic, petroleum migration, petroleum accumulation