Abstract: The ascending descending base levels cause that facies series in ffectively allowed spaces shifts landward and basinward. The curves of base level changes can be made based on this principle. This method is elaborated by examples of the fluvial strata of Permian in Sulige gas field. The quasi-sequences in the target zones are divided into five types in terms of individual sedimentary facies and energy, and they form a facies series along the water flow. Hence, the studied area could be divided into three sections: upper reach, middle reach and lower reach. Stat and choose the best frequent quasi-sequence in each one, then link all the quasi-sequences in each section, and make curves of the base level changes. These curves are testifed quantitatively by the varied Iread of average thickness in sand body of over 1m.

Key words: Sulige gas field, stream, base level, sequence, type