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鄂尔多斯盆地长北气田山西组2段为一套海相辫状河三角洲沉积体系,为揭示不同时期小层砂体发育规模及空间分布,以高分辨率层序地层分析为基础,相控建模为指导思想,短期基准面旋回为地层单元,等时地层格架为约束条件,采用序贯指示数学方法对长北气田山2段4个短期层序的水上分流河道、水下分流河道及河口坝微相小层砂体的发育规模及空间分布进行了随机模拟。砂体展布的三维模拟结果表明,河道自北向南沿物源方向延展,其中SSC1～SSC4短期基准面上升时期,河道加宽,小层砂体沉积厚度加大,物性较好,有利储层发育;下降时期河道变窄,小层砂体沉积厚度减小,物性变差。小层砂体的三维模拟结果在该区勘探实践中得到了很好的验证。
The 2nd member of Shanxi Formation in the Changbei gas field of the Ordos Basin is a set of marine braided river delta sedimentary systems. To reveal the developmental scale and spatial distribution of small sand bodies in different periods, based on high resolution sequence stratigraphic analysis, As the guiding ideology, short-term base-level cycles are stratigraphic units and isochronal stratigraphic framework as constraints. Four short-term water distributary channels, underwater distributary channels and estuaries The developmental scale and spatial distribution of the dam microfacies small sand body are simulated stochastically. Three-dimensional simulation results of sand body distribution show that the river course extends along the provenance direction from north to south. In SSC1-SSC4, the short-term basement rises, the channel broadens, the sedimentary thickness of small sandbodies increases, and the physical property is good. The river channel narrowed down in the descending period, the sedimentary thickness of the small sand body decreased, and the physical properties deteriorated. The results of 3D simulation of small sand bodies have been well verified in the exploration practice in this area.