须家河组多物源的沉积物理模型设计

Design of Physical Model for Multi-source Sediment in Xujiahe Formation

四川盆地上三叠统须家河组具有砂体展布面积广,沉积厚度大,多物源发育,各物源沉积体系类型变化大,沉积期次多的特征。为了重现大面积砂体沉积过程和结果,特对须家河组多物源进行物理模型设计。由于模拟试验需要体现不同物源、不同时期及不同部位的沉积特征,在模型设计中,试验设计3个物源,模拟6个层段,采用相似原理与自然模拟法相结合的方法进行模型设计,来尽可能逼近原型沉积特征。先明确模拟区域的地质条件,结合模拟区域及试验装置的特征,通过相似法则建立原型与模型的相似关系,确定边界情况,设计物源特征、模拟过程活动底板沉降量及模拟各期的湖水位变化等;再采用自然模型法,对试验模拟试床水动力参数设计,得到塑造河床的平均深度、流量及流速各水动力参数;再通过试床试验及经验对试验参数进行反复调整并验证,最终确定试验模型所需的各物理量。

The upper Triassic Xujiahe Formation in Sichuan Basin had the characteristics of wide distribution of sandbodies,big thickness of sediments,growth of multi-sources,big changes of the multi-source sediments and various periods of sediments.To represent the results of large scale of the sediments,a physical model was especially designed for the multi-sources in Xujiahe Formation.Because the features of different sources,different times and different positions were needed for simulation experiments,in the model design,3 sources were designed and six formations were simulated.Similitude principle combined with naturalness simulation principle was used for model design to present the real sedimentation characters.By using the similitude principle,the similitude correlation was established between the primary type and model for determining the boundary and designing the source features,settling the volume of flexible floor and the changes of the lake level.The hydrodynamic parameters were simulated for the experiment by naturalness simulation principle.The experimental parameters are repeatedly adjusted and validated by test-bed experiment and experiences,and the physical quantities required for experimental model are eventually determined.