| Based on outcrops, rock cores,3- D seismic and well and logging data, mainly by means of advanced seismic theories of sedimentoligy, high resolution sequence stratigraphic theory and reservoirs prediction, an extensive and indepth studying on the 8th member of lower Shihezi of Su-6area in the Ordos Basin. A series of theoretical viewpoints and research fruition are concluded as follows:1 .The author set up the braided channel in the lower part of 8th member of Lower Shihezi Formation and the more-channel and low-sinuosity meandering river in the upper part of 8th member of Lower Shihezi Formation sedimentary models, and think that the most favorable reservoir is overriding sand bodies of channel bar and point bar.2.The authors distinguish two long-term, four middle-term and eleven short-term cyclic sequences through taking the as a direction and analyzing sequence structure and stacking pattern of base-level cycle in sedimentary dynamic, In this paper, the structure, stacking distribution sedimentary cycles and stacking patterns of different cyclic sequences , in which the characteristics of different type of sand are discussed in detail.3.By means of seismic stratigraphy and sequence stratigraphy,based on long-term and the MFS, author establishes the chrono-stratigraghic framework , middle-term and short-term cycle sequences framework.4.According to sequence-lithofaceis palaeogeographic method, the authors confirm middle-term and short—term cycle sequences sedimentary faces and sands distribution map. By means of seismic stratigraphy and forward modeling, set up the "strough peak and trough "seismic response model of rhe gas-bearing sandstone and predict the gas bearing sandstone.5.The author think that the gas controed by the sandstone distributing of middle-term and short-term cycle sequences, predicted effective reservoirs and the rich zones of gas, well site and the area of the future exploration are pointed out.
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