长北气田山2段小层砂体三维建模

THREE-DIMENSIONAL MODELLING FOR SMALL LAYER SAND-BODY OF THE SECOND MEMBER OF SHANXI FORMATION IN CHANGBEI GAS FIELD

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 second member of Shanxi formation is a marine facies braid river delta sedimentary system in Changbei gas field,Ordos Basin.In order to reveal small layer sand body development scale and space distribution in different time,in this paper,taking high resolution sequence stratigraphic analysis as foundation,facies-controlling modelling as guiding ideology,short base-level cycle as formation unit and equitime stratigraphy framework as constraint condition,sequence indicator simulation method is used to simulate four short sequence braid river delta distributary channels,submerged distributary channels and river mouth bar small layer sand body development scale and space distribution on the second member of Shanxi formation in Changbei gas field.Sand body space distribute simulation result shows the channel flows from north to south and SSC1─SSC4 short base-level ascending phase is the best phase for sand body development.The channel width turned wider,sediment thickness increased,physical property turned to better,and these are good for reservoir to develop,but in descending phase,channel width turned thinner and small layer sand body thickness decreased.The small layer sand body three-dimensional simulation result gets a good validation according to actual exploration in this area.