The Numerical Model Of Sedimentary Processes In Braided River

Braided river is a common and greatly important sedimentary type in nature,predecessors have done a lot of research on braided river sediments,however,most of them were based on qualitative research,with the focus on local and microscopic research,poor correlation,insufficient understanding of the whole and macroscopic,and lack of relevant quantitative analysis.In this paper,through the study of the sedimentary process of braided river based on numerical simulation,the complete dynamic evolution process of braided river was established,and the influence of different controlling factors on sedimentation was analyzed,which will provide a new idea and research method for more accurate characterization of braided river reservoirs or prediction of unknown types of reservoirs,and providing guidance for oil and gas exploration and development.Different from the traditional sedimentary physical simulation method,this paper is used in sediment numerical simulation method,borrowing the forefront of the results of computational fluid dynamics,numerical simulation not only plays an important role in understanding the deposition of braided river,the study also provides a new method and means for the geologists.On the basis of preliminary research on a number of related literature,based on the hydrodynamic characteristics of the modern braided river,the hydrodynamic and sediment simulation conditions were designed,the braided river model was established by Delft3 D sedimentation numerical simulation software.Analysis of the evolution of braided river deposition based on simulation results,the simulation results show that the sedimentary evolution process of the braided river in the early stage of the model is similar to that of the delta;at the stable stage of the model,the development of the dam becomes slower,which is similar to the sedimentary characteristics of the reticulated river.Through the single model analysis,it was clarified that the head of the dam was eroded by the upstream flow,the head of the dam was gradually eroded,and the tail was subjected to sedimentation,the dam moved downstream macroscopically;at the same time when the dam was migrating downstream,due to the asymmetry of the braided channel on both sides of the dam,erosion on the side of the main channel and sediment on the side of the secondary channel,the overall performance was the lateral migration of the dam;in addition,when the dam reached a certain size and height,relative low-lying place on the top of the dam was washed by the water stream,and the secondary small water channel at the top of the dam was gradually formed,this was also a kind of diversion effect,for the lower flow velocity of the braided channel and the dam gradually tended to be stable had a certain effect.Through comparison of several models,the sedimentary characteristics of braided river under different control factors were analyzed,including river flow,sediment concentration,sediment ratio and water level.Sedimentary numerical simulation using computational fluid dynamics can reproduce well the deposition of braided river,not only directly reflect the development and evolution of the sedimentary body,also provide quantitative data for the study of geological,it can be seen that it is of great significance as a new technology for the subsequent study of sedimentology,and an important tool for theoretical research sedimentology from qualitative to quantitative.