Stochastic Simulation Of Continuum Networks And Solute Transport In Fractured Media

With the rapid development of petroleum and nuclear industry,Characterization of fractured rock and the solute transport inside fractured media have been widely concerned,and become one of the most challenging problems in hydrogeology field.This is because fractured media is not only the natural storage reservoir transportation channel for oil and gas resources,but also geological disposal repository of nuclear and industrial waste.Identification,prediction and quantitative characterization of the distribution of fractured media and establish fracture network model are the essential problems to effectively explore and develop oil and gas resources,and prevent contamination caused by leakage.However,fractured media has a strong spatial variability and great anisotropy,which leads to the occurrence of groundwater also exists heterogeneity.The key to simulate fractured media lies in the description of its geometric features,so it is critical to find a proper way to accurately delineate the geometric features of fractured media.Geometric features of fractured media include fracture density,location,length,direction,and so on.However,most of the fractures are buried deeply underground,their geometric characteristics cannot be measured directly,the distribution of fractures in space are very uncertain,but also follow some certain distribution regulations.Therefore,based on the principle of statistics,we can establish fracture network models with the method of stochastic simulation.Base on the understanding and summarization of research progress,the study of stochastic simulation and solute transport in fracture networks has been carried on with two stochastic methods:Boolean simulation and multi-point geostatistics.The research progresses are as follows:Firstly,the development of fracture network models is reviewed;the merits and drawbacks of different kinds of fracture models are discussed.Then,we introduce the operation principles and simulation processes of two methods:Boolean simulation and multi-point geostatistics.Secondly,Boolean method and multiple-point statistical simulation are introduced to establish fracture network models of a specific field.We compare the Geometrical parameters with real data,such as length and orientation,to assess its characterizing accuracy.Finally,the two methods are used to establish and calibrate a specific two-dimensional fracture network model.Also,the generated models are combined with MODFLOW and MT3DMS codes to simulate flow and solute transport in fracture networks.The simulation results show that solute in fracture networks is transporting strictly over time in agreement with the orientation of the fractures.Furthermore,as the conductivity ratio between channel and matrix increases,the phenomenon of anisotropy and preferential flow becomes much more obvious.It is shown that the statistical simulation provides a powerful tool for characterizing complicated fracture networks as well as simulating the flow and solute transport in fracture networks.