Abstract: Qingxi field is located in middle of overthrust nappe in northern margin (Kulongshan) of Qilianshan mountain where intensive piedmont fold is associated with a series of huge overthrust fault structures which are characterized by advanced and imbricate overthrust faulting toward surface and related folds. In order to structural feature and hydrocarbon enrichment, this paper presents in-depth analysis of the faulting structures and detailed interpretation of a variety of crude-controlled faults or structures, as well as fractural prediction and oil-controlled mechanism, showing its distinctive features of oil-gas distribution. It is concluded that the tear faulting of N-E trend shaped in overthrust fault front controls effective development of fractural belt, which could be high-yielding blocks in Qingxi field.

Key words: Jiuquan basin, Qilianshan mountain, Qingxi field, overthrust fault, structural belt, structural feature, fracture, oil-gas reservoir distribution