Abstract: According to synthetic core, logging and seismic data from Shawan formation of Neocene in Chepaizi area of Junggar basin, the Shawan formation could be divided into two sequences of Class III. Its unconformity surface as the sequence boundary of Shawan formation can be identified from the seismic profile and well section. The determination of maximum lake flooding surface is based on the changing of stratigraphic superposition pattern, lithology and logging curves, which is the key of the division of systems tract. The study shows that the structure of this area assumes a large-scale slope without distinct slope break, so the sequence stratigraphic model for a basin with gentle slope without continental slope break can be developed. In control of unitary structural framework, the development of Shawan formation should be controlled by the sediment supply rate, the climate and the change of lake level. Also, the favorable reservoir-cap rock assemblages are predicted using sequence stratigraphic theory integrated with oil entry features of Well Che-89 and Che-95.

Key words: Junggar basin, Chepaizi, Neocene, model, sequence