Simulation Study On Transport Law Of Proppant In Complex Fractures

After completion,the natural productivity of low permeability and tight reservoirs is low or non-productivity,which requires SRV fracturing to form complex network fractures before having industrial production.The placement of proppants have an important influence on the activation of natural fractures and the formation of complex fracture networks.At present,domestic research on proppant placement in complex fracture network started late,and the proppant migration law in complex fracture is still unclear.In view of this,this paper takes large-scale visual multi-fracture experimental device as a means to carry out experimental research on proppant type,fracturing fluid,proppants adding method,perforation method and other factors affecting proppant migration in a single fracture.The influence of each factor on proppant migration is quantitatively analyzed by using the characterization parameters such as balance hight,proppant-laying area and non-uniformity,and the construction parameters are optimized.On the basis of the optimized parameters,a multi-factor complex fracture experiment is designed.The effects of fracture model,pump rate and proppants concentration on proppant migration are analyzed.The effects of various factors on the shape of proppant laying are quantitatively analyzed by correlation analysis method.On the basis of physical model experiment,the corresponding 3-D physical model is constructed by SolidWorks software,and the complex fracture mesh is drawn by ICEM software.Then,based on CFD method,proppant transport in the fracture is simulated by Fluent software,and the proppant migration and steering law is further analyzed by velocity vector diagram.Through the above research,this paper mainly obtains some understandings:(1)Through single fracture experiment,we can select two kinds of technology:large-section multi-cluster perforation and pulse pump injection,which are beneficial to proppant transport to the depth of the fracture;fiber fracturing fluid can effectively improve the proppant carrying capacity of fracturing fluid,and it is suggested to adopt the combination of medium-sized and small-sized proppant filling.The proppant laying formed by the combination of medium-sized proppant filling and small-sized proppant filling can meet the characteristics of a Relatively height,long distance of proppant laying.And the proppant proportion of small particle size is not more than 50%.(2)Through complex fracture experiments,it can be concluded that the smaller the angle of branch fracture is,the easier the proppant enters the branch fracture;the larger the pump rate and proppant concentration is,the easier the proppant enters the branch fracture,and the more obvious the influence of proppant concentration on the proppant laying in the main fracture and branch fracture,but the farther the branch is from the wellbore,the more the influence of displacement on the proppant laying area increases gradually;The proppant is easier to steer.3.The correctness and feasibility of the simulation model are verified by comparing the results of experiment and numerical simulation.At the same time,the proppant steering is divided into two situations by using the simulation results,and the proppant migration law is analyzed,which provides a basis for the fracturing construction design.